The effects of diabetes on the recovery of motor nerve function after cervical decompression surgery and associated mechanisms

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Methods The medical records and follow-up data for patients with cervical spondylosis who underwent cervical spine surgery from January 2021 to December 2023 were retrospectively analysed. The patients were divided into diabetes mellitus (DM) and non-DM groups. The clinical characteristics, preoperative and postoperative Japanese Orthopaedic Association (JOA) scores, JOA recovery rates (JOA-RR), neck disability index (NDI) values, and visual analogue scale (VAS) scores for the two groups were compared, and factors independently associated with motor nerve function recovery were identified via multivariable linear regression analysis. The findings of these analyses were validated in animal experiments involving adult male Sprague‒Dawley (SD) rats with type 2 DM and the same number of healthy SD rats as the control group. Both groups of rats underwent surgery to model incomplete cervical spinal cord injury. The forelimb locomotor assessment scale (FLAS) was used to evaluate the forelimb movement of the rats in the two groups on the 1 st , 7 th , 14 th , and 30 th days after surgery, and motor-evoked potentials (MEPs) were measured. The numbers of neurons and functional changes in the axons and other organelles of the samples at the site of injury to the cervical spinal cord were determined via electron microscopy and light microscopy on the day of and 30 days after the operation. Results A total of 129 patients who underwent cervical spine surgery were analysed in this study, including 59 in the DM group and 70 in the non-DM group. The median age, mean preoperative glycosylated haemoglobin (HbA1c) level, mean preoperative glucose level, and mean volume of intraoperative bleeding in the DM group were greater than those in the non-DM group, whereas the JOA, JOA-RR, NDI, VAS neck (VAS (N)), and VAS limbs (VAS (L)) scores within six months after surgery were greater for the non-DM group than for the DM group. Multivariate linear regression suggested that age and the preoperative HbA1c level were independently associated with the postoperative JOA score, the preoperative blood glucose level was independently associated with the postoperative NDI, and the surgical segment and preoperative blood glucose level were independent risk factors for the postoperative VAS (L) score. The animal experiments revealed that both groups of rats began to recover motor nerve function within 7 days after incomplete cervical spinal cord injury; the FLAS score of the non-DM group on the 7 th and 14 th days was greater than that of the DM group, whereas the FLAS score on the 30 th day was not significantly different between the two groups. Compared with those of individuals in the non-DM group, the latency and amplitude of upper-extremity MEPs were both lower for individuals in the DM group. The latencies of the lower-extremity MEPs were similar, but their amplitudes were lower for the DM group than for the non-DM group. Under light microscopy, the individuals in the DM group presented more severe spinal cord tissue necrosis, a more severely scattered central canal, and fewer neurons in the affected area than did the individuals in the non-DM group. Under high-resolution electron microscopy, in the DM group, the axons exhibited lamellar separation and tissue swelling, and the tissue structure was incomplete on the 30 th day after surgery. Conclusions The poor recovery of motor nerve function observed in DM patients following cervical decompression may be related to neuronal necrosis and loss and axonal degeneration caused by the high-glucose environment in these individuals. diabetes mellitus cervical spine surgery motor nerve function neuronal cells axonal degeneration rat animal experiment Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Backgrounds Some patients with cervical spondylosis experience poor functional nerve recovery after surgery and may even experience paralysis of the innervated area that is not present before surgery; these complications are especially prominent in patients with diabetes mellitus (DM). The main factors that negatively affect the efficacy of cervical surgery include hypertension, advanced age, multisegment decompression and fusion, intraoperative intervertebral space hyperextension, postoperative spinal cord drift, nerve root stretching, and ischaemia‒reperfusion injury [ 1 – 6 ] . Among patients receiving spine surgery, 5–20% have DM [ 7 ] ; however, the effect of DM on surgical results, especially in terms of nerve recovery, is still poorly understood. DM is caused by insulin deficiency, impairment of certain biological functions, or both. The worldwide prevalence of DM among adults aged 20–79 years was approximately 285 million in 2010 and is expected to increase to 439 million by 2030 [ 8 ] . Chronic hyperglycaemia not only causes organ system damage, dysfunction or failure but also has serious effects on the nervous system [ 9 ] . Diabetic peripheral neuropathy, damage to the nerves of the distal limbs, is one of the most common complications of DM [ 10 , 11 ] . Moreover, DM can also affect the central nervous system [ 12 ] . Many reports have confirmed that DM is a risk factor for adverse clinical outcomes and an increased incidence of complications after lumbar surgery, including surgical site infection [ 13 ] , prolonged hospitalization and increased hospitalization costs [ 14 ] , poor postoperative neurological recovery [ 15 , 16 ] , and increased reoperation rates [ 17 ] . However, studies of the clinical effects and complications of cervical spine surgery in DM patients are scarce. In this study, the data for 129 patients who underwent cervical spine surgery at the Department of Orthopaedics, Beijing Tiantan Hospital, Capital Medical University, were retrospectively analysed. Patient age, mean preoperative glycosylated haemoglobin (HbA1c) level, mean preoperative blood glucose level, mean volume of intraoperative bleeding, operative segment, mean hospitalization length of stay, mean hospitalization costs, Japanese Orthopaedic Association (JOA) score, visual analogue scale (VAS) score, JOA recovery rate (JOA-RR), and neck disability index (NDI) for the patients in the DM group were compared with those of individuals in the non-DM group, and the effect of DM on motor nerve function recovery after cervical decompression was evaluated. Moreover, incomplete cervical spinal cord injury was established in type 2 DM rats, and changes in postoperative limb activity, motor-evoked potentials (MEPs), and the number of neurons and changes in the axons and other organelles at the site of injury were analysed to explain the poor motor nerve function recovery following cervical decompression due to pathological changes induced by DM. Materials and methods Patients Between January 2021 and December 2023, 129 patients who underwent cervical spine surgery at the Department of Orthopaedics, Beijing Tiantan Hospital, Capital Medical University, were included in this study. Patients were included on the basis of the following criteria: (1) the presence of a cervical degenerative disease; (2) incomplete cervical spinal cord injury; and (3) follow-up duration ≥ 1 year. Patients were excluded if they met the following criteria: (1) had type 1 DM; (2) long-term use of steroids; (3) had cervical spinal cord injury or cervical spondylosis supported by imaging studies but lacking symptoms of clinical nerve injury; (4) had complete cervical spinal cord injury; (5) had a cervical tumour or infection; (6) had cervical revision; or (7) had incomplete medical records. According to the type of cervical spondylosis and the presence of DM before surgery (Chinese Diabetes Guidelines 2024, regarding diagnostic thresholds: (1) typical symptoms of diabetes; (2) random plasma glucose ≥ 11.1 mmol/L; and (3) fasting plasma glucose ≥ 7.0 mmol/L or HbA1c ≥ 6.5%), patients were divided into a degenerative cervical spondylosis combined with DM group (Group A, n = 51), a degenerative cervical spondylosis and non-DM group (Group B, n = 53), an incomplete cervical spinal cord injury combined with DM group (Group C, n = 7), and an incomplete cervical spinal cord injury and non-DM group (Group D, n = 18). The study was approved by the Ethical Committee of Beijing Tiantan Hospital, Capital Medical University (KY2022-248-02). Surgical techniques All surgeries were performed by the same experienced surgeon. The surgical methods included anterior cervical canal decompression, anterior cervical discectomy and fusion (ACDF), anterior cervical corpectomy/fusion (ACCF), posterior cervical single-door laminoplasty, and posterior cervical laminectomy. Evaluation of neurological function A comprehensive neurological examination was performed before the operation and at 1 month, 6 months, 1 year, and 2 years after surgery, during which the NDI score, JOA score, and JOA-RR were used to quantify the degree of neurological deficit, and the VAS score was used to assess the degrees of cervical pain (VAS neck (VAS (N)) score) and limb pain (VAS limbs (VAS (L)) score). The JOA-RR formula was as follows: (total postoperative score - total preoperative score)/ (17 - total preoperative score) × 100%. Animal preparation The animal experiments were performed at the Animal Laboratory of the Beijing Neurosurgical Institute. The study protocol was approved by the Ethics Committee of Beijing Neurosurgical Institute (ethics number: 2024363). All animal experiments were conducted in accordance with the Guidelines for the Institutional Animal Care and Use Committee. Fifty adult male SPF-grade Sprague–Dawley (SD) rats (weighing approximately 200 g) were purchased from Jinan Pengyue Experimental Animal Breeding Co., Ltd. All the animals were evenly divided into 2 groups (Group A and Group B), with 25 rats in each group. The rats in Group A were given ear tags numbered 1–25, and those in Group B were given ear tags numbered 26–50. Type 2 DM rat model The rats in Group A were fed high-sugar, high-fat, semisynthetic high-calorie feed (D12451; 15% lard, 20% sucrose, 10% egg yolk powder, 1% cholesterol, 0.2% cholate and conventional feed) purchased from Xiaoshu Youtai (Beijing) Biotechnology Co., Ltd. The Group A rats were fed to induce insulin resistance, whereas Group B rats were fed conventional feed. Following a 2-week acclimatisation period, the rats were fasted (with ad libitum access to water) for 18 hours. Group A (diabetic cohort) received a single intraperitoneal injection of streptozotocin (STZ; 35 mg/kg). Blood glucose levels were measured via tail vein sampling at 72 hours post-injection and subsequently twice weekly. Diabetes induction was confirmed if random glucose levels were ≥ 11.1 mmol/L and fasting glucose levels were ≥ 7.0 mmol/L. Nonresponsive rats underwent repeat STZ administration after a 3-day observation period. When rats with blood glucose ≥ 22 mmol/L accompanied by behavioural abnormalities (altered respiration or consciousness) received Novolin N, 3 IU/day subcutaneously for 3–5 days, glucose levels between 11.1–20 mmol/L were maintained. The Group A rats were provided unrestricted food/water with daily bedding replacement. Modelling of incomplete cervical spinal cord injury Surgical modelling was performed for Groups A and B rats. After the rats were anaesthetized via intraperitoneal injections of pentobarbital sodium (30 mg/kg), they were fixed in the prone position on the operating table, the limbs were immobilized, the hair from the cervical spine was removed, and the lower cervical spine was slightly elevated with gauze and a cotton pad. The tongue was pulled out of the mouth to avoid suffocation. The skin and subcutaneous tissue were incised with a scalpel. Then, the spinous processes and some muscles around the lamina were isolated, after which the C5-C6 spinous processes and part of the lamina were exposed and removed to expose the cervical spinal cord. A modified Allen technique was used to induce incomplete spinal cord injury; specifically, a 20 g Kirschner wire with a diameter of 4 mm was dropped from a height of 3.5 cm through a hollow tube to injure the cervical spinal cord in the area exposed at C5-C6. The establishment of the rat cervical spinal cord injury model was confirmed after congestion appeared at the site of injury, and the rat experienced shaking of the hind limbs or all four limbs and spasmodic swing of the tail. Antibiotic irrigation solution and normal saline were used to rinse the wound, after which the wound was closed. After the rats woke, the animals were administered the analgesic buprenorphine (0.05 mg/kg). The rats were kept in separate cages and given free access to water and food under a 12-hour light/dark cycle. The room was well ventilated and maintained at a temperature of approximately 26°C and 30%-60% humidity. The rats were encouraged to eat daily, and their bladder was compressed 3 times a day until spontaneous urination was restored. Behavioural assessment The forelimb locomotor assessment scale (FLAS) [ 18 ] was used to evaluate the forelimb motor function of the rats in Groups A and B on the day of the operation and 7, 14, and 30 days after incomplete cervical spinal cord injury. Motor-evoked potential At postoperative days 0 (model establishment), 7, 14, and 30, four randomly selected rats per group were anaesthetized via intraperitoneal injection of pentobarbital sodium (30 mg/kg) and subjected to neurophysiological assessments. MEP recordings were acquired using needle electrodes under standardised conditions: the animals were positioned in lateral recumbency, with biparietal stimulating electrodes placed on the cranial vertex and recording electrodes positioned over the bottom of the biceps brachii or gastrocnemius muscles. The stimulation consisted of dual 10-mV pulses delivered at 0.1–1 Hz, with the intensity adjusted to elicit observable muscle contraction in the target muscles. The signals were amplified, filtered, and recorded using electromyography. To ensure protocol standardization, triplicate measurements were performed per session with 3-minute intervals between trials. Optimal waveforms were selected on the basis of the shortest latency and highest amplitude, with a mean maximum stimulation current of 26 mA applied across all sessions. Tissue processing, storage and observation methods After MEP induction and recording, the rats were euthanized with an overdose of pentobarbital sodium (50 mg/kg), after which the spinal cord at the surgical site was quickly removed, opened longitudinally and soaked in 2.5% glutaraldehyde fixative solution at room temperature. After 1 h, the spinal cord was stored at 4°C overnight, washed, dehydrated, embedded in paraffin, sectioned at a thickness of 5 µm, and stained with haematoxylin‒eosin (HE) for observation under an upright light microscope. Another part of the spinal cord from the same rat was subjected to the same procedure as described above until washing, where it was fixed in osmic acid, infiltrated with ethylene oxide, and embedded in resin. The spinal cord was cut into 70-nm-thick cross-sections, which were then stained with 2% uranyl acetate solution and lead citrate staining solution. The sections were assessed via transmission electron microscopy (TEM). Statistical analysis SPSS 27.0 software was used for data analysis, and a two-sided p value < 0.05 indicated statistical significance. The measurement data wee expressed as medians, minimum and maximum values, effective numbers of cases, and means ± standard deviations. The counting data are presented as percentages. The Kolmogorov‒Smirnov method (with a sample size greater than 50) and the Shapiro‒Wilk method (with a sample size less than 50) were used to test the normality of the samples. Intergroup comparisons were performed with the independent samples t test for normally distributed data, the rank sum test (Mann‒Whitney U test or Wilcoxon rank sum test) for nonnormally distributed data, and the χ2 test or Fisher's exact test for count data. GraphPad Prism 8.0.2 software was used to create charts. The risk factors for poor neurological recovery after cervical surgery were analysed using univariate and multivariate linear regression models. Results Clinical characteristics A total of 129 patients with cervical spondylosis were analysed, including 59 patients in the DM group and 70 patients in the non-DM group. The clinical characteristics of the patients are summarized in Table 1 . The median age, preoperative mean HbA1c level, mean preoperative blood glucose level, and mean intraoperative blood loss in the degenerative cervical spondylosis combined with DM group were greater than those in the corresponding non-DM group ( p < 0.05), and the preoperative mean HbA1c level, mean preoperative blood glucose level, mean intraoperative blood loss, mean length of hospitalization stay, and mean hospitalization costs in the incomplete cervical spinal cord injury combined with DM group were greater than those in the corresponding non-DM group ( p < 0.05). Table 1 Clinical Characteristics of patients DM (N = 59) Non-DM (N = 70) p Group A (n = 51) Group B (n = 53) p (A vs B) Group C (n = 8) Group D (n = 17) p (C vs D) Age 63 (34–79) 56 (24–77) 0.000 64 (34–79) 57 (39–76) 0.000 58 (38–75) 55 (24–77) 0.440 Gender 0.833 0.812 0.726 male 36 44 31 (60.8) 31 (58.5) 5 (62.5) 13 (76.5) female 23 26 20 (39.2) 22 (41.5) 3 (37.5) 4 (23.5) Glycohemoglobin 8.0 ± 1.8 5.7 ± 0.8 0.000 8.0 ± 1.8 5.8 ± 0.8 0.000 8.5 ± 2.1 5.7 ± 0.7 0.000 Blood glucose 7.9 ± 2.7 5.1 ± 0.7 0.000 7.7 ± 2.6 5.0 ± 0.6 0.000 8.7 ± 3.1 5.2 ± 0.7 0.000 Hospitalization day 14.0 ± 6.1 10.8 ± 3.5 0.000 13 (5–34) 12 (5–21) 0.127 13 (8–40) 7 (4–11) 0.000 Hospitalization expenses 96316.1 ± 35670.0 86375.4 ± 23313.2 0.060 93903.7 ± 33979.7 92436.0 ± 21605.6 0.793 111393.2 ± 44461.8 67480.7 ± 18049.0 0.002 Peroperative bleeding 54.9 ± 37.1 35.5 ± 18.5 0.000 45(10–500) 30(10–100) 0.002 80 (50–500) 40(20–100) 0.005 Operative segment 3 (1–4) 2 (1–4) 0.170 3 (1–4) 2 (1–3) 0.041 1 (1–2) 2 (1–4) 0.087 DM, diabetes mellitus. Group A, degenerative cervical spondylosis combined with DM group. Group B, degenerative cervical spondylosis and non-DM group. Group C, incomplete cervical spinal cord injury combined with DM group. Group D, incomplete cervical spinal cord injury and non-DM group. Postoperative neurological recovery The JOA score, JOA-RR, NDI, VAS (N) score, and VAS (L) score of all patients before surgery and at 1 month, 3 months, 6 months, 1 year, and 2 years after the operation were recorded. The JOA score, JOA-RR, NDI, VAS (N) score, and VAS (L) score improved 1 month after surgery relative to the preoperative values for each of the four groups (Supplementary Tables 1–4). Regardless of the type of cervical spine disease, the JOA score, JOA-RR, NDI, VAS (N) score, and VAS (L) score six months after surgery were better in the non-DM group than in the DM group ( p < 0.05) (Figs. 1 – 5 , Supplementary Table 5–9). Preoperative HbA1c level, age, intraoperative blood loss, surgical segment, and preoperative blood glucose level were identified as significant predictors of poor outcomes in the univariable linear regression analyses. Subsequent multivariable linear regression indicated that age and preoperative HbA1c were independent predictors of postoperative JOA (R 2 = 0.209, △R 2 = 0.194, F = 13.36, P < 0.01), the preoperative blood glucose level was an independent predictor of postoperative NDI (R 2 = 0.088, △R 2 = 0.079, F = 9.788, P < 0.01), and the surgical segment and preoperative blood glucose level were independent predictors of the postoperative VAS (L) score (R 2 = 0.168, △R 2 = 0.151, F = 10.171, P < 0.01) (Table 2 – 4 ). Table 2 Multiple Linear Regression Analysis of JOA item B S.E. β t value p Glycohemoglobin − .330 .094 − .312 -3.511 .001 Age − .063 .019 − .303 -3.399 .001 Y = 21.16–0.33× preoperative HbA1c level − 0.063× age (R 2 = 0.209, △R 2 = 0.194, F = 13.36, P < 0.01) Table 3 Multiple Linear Regression Analysis of NDI item B S.E. β t value p Blood glucose 0.999 .319 .296 3.129 .002 Y = 2.774 + 0.999× blood glucose (R 2 = 0.088, △R 2 = 0.079, F = 9.788, P < 0.01) Table 4 Multiple Linear Regression Analysis of VAS(L) item B S.E. β t value p Blood glucose .315 .075 .403 4.355 .000 Operative segment − .432 .216 − .185 -2.000 .048 Y = 0.716 + 0.315× blood glucose − 0.432× operative segment (R 2 = 0.168, △R 2 = 0.151, F = 10.171, P < 0.01) Successful modelling of type 2 DM rats One week and one month after STZ injection, the rats in Group A presented significant polydipsia, polyphagia, polyuria, and weight loss. The measurement of random blood glucose from the tail vein yielded a 100% success rate for establishing rat models of type 2 DM, as confirmed by sustained hyperglycaemia. The blood glucose levels of individuals in Group A after one month were greater than those of individuals in Group B ( p < 0.05), whereas the body weights were lower in Group A than Group B (Table 5 ). Table 5 Blood glucose and weight of rats Blood glucose and weight Group A Group B p Modeling 1-week of random blood glucose values 18.99 ± 2.89 7.98 ± 1.73 <0.001 Modeling 1-month of random blood glucose values 16.11 ± 2.48 7.30 ± 1.70 <0.001 Modeling 1-month of weight 468.55 ± 64.41 667.44 ± 30.92 <0.001 A B Behavioural results During the modelling of incomplete cervical spinal cord injury, most of the rats in the two groups exhibited tetraplegia, were unable to walk and could only raise their heads, whereas a small number of the rats in Groups A and B exhibited slight flexion of the elbow and shoulder joints. Moreover, there was no significant difference in the FLAS score ( p > 0.05) between the two groups. After 7 days, the rats in the two groups could stand on their limbs, but their wrist and grip strength were poor when eating, and the FLAS score of Group B was higher than that of Group A ( p = 0.036). After 14 days, the rats in the two groups moved around freely. However, a few rats in the two groups still displayed poor grasping ability; the FLAS score of Group B was higher than that of Group A ( p = 0.043). After 30 days, the rats in the two groups were able to move freely, suggesting that their motor function had essentially recovered. The grip strength of one rat in Group A did not recover, however, and it needed assistance maintaining its head when eating. There was no significant difference in the FLAS score between the two groups at 30 days ( p > 0.05) (Fig. 6 ). Somatic MEPs Compared with Group B, Group A demonstrated prolonged latency and reduced amplitude in both the upper and lower limbs at 1 month post-modelling, although the amplitude reduction in the lower limbs was less pronounced than that in the upper limbs. (Fig. 7 ). On the day of incomplete cervical spinal cord injury modelling, the latencies of the MEPs of the upper limbs and lower limbs of the rats in Group A and Group B were similar, and the amplitudes were low; moreover, the amplitudes were significantly lower than those of the uninjured rats in the same group. On days 7 and 14 after modelling, a gradual improvement was observed in the amplitude and latency of the MEPs in both groups of rats, and by day 30 of modelling, the recovery had peaked. However, within-group comparisons revealed that the amplitude was still smaller than that before modelling in both groups (Fig. 8 ). Histological observation During the establishment of the rat model of incomplete cervical spinal cord injury, the sites of injury in Groups A and B were observed via light microscopy. The area surrounding the injury site revealed tissue necrosis, which was more severe in the white matter than in the grey matter, as well as vascular proliferation and loss of neurons. Despite the same degree of injury, Group A rats presented more severe tissue necrosis and scattering of the central canal (for both the grey matter and white matter) and fewer neurons in the peripheral grey matter than Group B rats did. A small number of neurons and some axonal tissues could still be observed in Group B. In the 50× magnified histological sections, both groups A and B exhibited discernible anatomical architecture and trajectories of the anterior corticospinal tracts, containing abundant nerve fibre cells—a histological manifestation indicative of preserved conductive functionality in both cohorts. However, comparative analysis revealed that group B demonstrated superior structural integrity for these neural pathways, as evidenced by more coherent axonal cell arrangement (Fig. 9 ). One month after the modelling began, a large amount of gliosis was observed in the area surrounding the injury site in the two groups. Under 50× microscopic examination, histological analysis of the anterior horn regions of the spine revealed distinct intergroup variations: Group A demonstrated a significant reduction in motor neuron density accompanied by an abundance of rounded glial cells, with the axonal architecture of residual motor neurons being non-discernible. In contrast, Group B exhibited well-preserved motor neuron populations with intact morphological characteristics coupled with minimal glial cell infiltration. These observations were substantiated by quantitative histomorphometric assessments and ultrastructural validation protocols (Fig. 10 ). High-resolution electron microscopy revealed that, 1 month after the establishment of the type 2 DM rat model, in Group A, the anterior horn motor neurons contained larger amounts of lipofuscin, and mild myelin sheath lamella separation and endoplasmic reticulum swelling were observed; in Group B, the boundaries of the anterior horn motor neurons were round, the myelin sheath lamella was dense, and the axons were clearly visible (Fig. 11 A-B). The corticospinal tract‒anterior horn interface of Group A rats also exhibited axonal injury, myelin sheath delamination, breakage, and dispersion, and severe internal axonal tissue swelling caused by typical hyperglycaemic factors was observed (Fig. 11 C). Comparative analysis of anterior horn motor neurons (1 month post-incomplete cervical spinal cord injury), Group A rats presented darker neurons with some areas of lipofuscin, some axonal tissue necrosis, persistence of separated and fractured axonal lamellae, and preservation of the internal axonal structure and function. In Group B, a small number of autophagosomes were present in the neurons, and the surrounding axons and myelin sheath were intact (Fig. 12 ). Discussion DM is one of the most common comorbidities among patients who undergo cervical spinal cord surgery. Studies have shown that neurological recovery in DM patients is poor following spine surgery, especially lumbar surgery [ 19 – 21 ] , primarily due to peripheral nerve microangiopathy and axonal demyelination [ 22 ] . These pathological changes have a significant impact on peripheral sensory nerves, yet few studies have investigated their effects on motor nerves. Studies have reported that the effect of DM on peripheral nerves is not limited to the lower extremities but also includes the peripheral nerves of the upper extremities; this effect is referred to as diabetic radiculoplexus neuropathy (DRPN) [ 23 ] . At the level of the cervical spinal cord, a significantly smaller cross-sectional area can be observed in the early stage of diabetic neuropathy than in healthy individuals [ 24 ] . In this study, during the 2-year follow-up of 129 patients who received cervical spinal cord surgery, the recovery rates of sensory and motor nerve function after surgery in DM patients were worse than those in non-DM patients, regardless of the form of injury (i.e., cervical degenerative disease versus incomplete cervical spinal cord injury surgery), particularly among patients with preoperative diabetic neuropathy. Most indicators improved within 6 months after surgery; however, at one year after surgery, the VAS (N) score and the NDI of the incomplete cervical spinal cord injury DM and non-DM groups (Group C vs. Group D) still differed. Multivariate regression analysis revealed that a high preoperative HbA1c level was correlated with a low postoperative JOA score, whereas the preoperative blood glucose level was positively associated with the postoperative NDI and VAS(L). These results suggest that long-term preoperative blood glucose status and preoperative blood glucose control are both important. This study revealed that the indicators of recovery for individuals in the incomplete cervical spinal cord injury combined with DM group were lower than those of individuals in the cervical degenerative disease combined with DM group. This may be related to the fact that in a long-term hyperglycaemic environment, the resistance of the tissues of the peripheral nerves and spinal cord to injury weakens. A retrospective study [ 25 ] revealed that DM patients are not as capable of exercising and require greater wheelchair use one year after cervical spinal cord injury, which is similar to the results of this study. In this research, animal experiments were used to explain and validate the observed clinical results. At the same injury strength, one month after cervical spinal cord surgery, the amplitude of the MEPs was lower and the latency was longer in the DM group than in the normal group. This study is the first to use electrophysiological examinations via an animal model to demonstrate that DM can impede the recovery of central nervous system function after cervical decompression. One study [ 26 ] revealed that, through electrophysiological examination after cervical spine surgery, DM was an independent risk factor for poor central nerve conduction after cervical decompression, and the surgical efficacy in patients who were insulin dependent for more than 10 years was poor. Under light microscopy, the rats in the DM group presented a larger cervical spinal cord injury area, fewer neurons in the field of view, and a more inconsistent morphology than did the rats in the healthy group. One month after incomplete injury, more glial cells populated the spinal cord of the rats in the DM group, further affecting neuronal conduction. Under electron microscopy, the dispersion of the lamellae was more severe, and the structures in the axons showed more obvious damage in the DM group, both of which can lead to demyelination of myelinated nerve fibres, indicating that DM also substantially affects the spinal cord through microangiopathy and axonal demyelinating lesions. Studies have shown [ 27 ] that in rats with incomplete cervical spinal cord injury, the spinal cord tends to display decreased glucose uptake, decreased neuronal cell viability, and significantly increased glial cell activation within 28–90 days after injury. This trend is amplified in DM rats because of the presence of perineural microvasculitis and vascular injury. In our experimental paradigm, equivalent current intensity stimulation revealed distinct MEP amplitude patterns between groups. The control rats (Group B) presented lower mean MEP amplitudes in the hindlimbs than in the forelimbs, whereas the diabetic rats (Group A) presented generalized amplitude reductions across all limbs. Notably, the magnitude of hindlimb amplitude reduction in Group A was less pronounced than that observed in the forelimbs than that observed for Group B. Two pathophysiological mechanisms may explain these findings: 1. Neuroanatomical vulnerability: The corticospinal tracts of the innervating hindlimbs reside in the anterolateral and lateral spinal cord regions. Mechanical forces originating from the posterior midline predominantly compromise the dorsomedial tracts governing forelimb function, rendering them susceptible to injury. 2. Electrophysiological correlations: MEP latency prolongation reflects demyelinating pathologies characteristic of diabetic microangiopathy, whereas amplitude reduction is correlated with α-motor neuron depletion and corticospinal conduction integrity. Post-cervical injury, forelimb motor deficits manifest most prominently because of this anatomical‒functional hierarchy. These experimental observations align with those of clinical MEP studies in patients with cervical spinal cord injury. Even at supramaximal stimulation intensities, healthy controls maintain lower baseline hindlimb than forelimbs MEP amplitudes. Injured patients exhibit amplitude reductions across all extremities, yet hindlimb values remain closer to normative ranges than forelimb measurements do, reinforcing the neurotopographical vulnerability gradient. For patients with cervical spondylosis combined with DM, cervical surgery for decompressing the nerve is crucial. For these patients, the surgeon should take care to determine the presence of a “double compression” effect [ 22 ] ; that is, in addition to the reduced motor and sensory ability of the upper limbs caused by cervical spondylosis, symptoms caused by the entrapment of nerves through other areas of stenosis in the upper limbs are often present. These effects are most likely to occur in DM patients, even in those with early-stage DM [ 28 , 29 ] . This study confirmed that in both DM patients and rats, nerve function recovery following cervical decompression was slow. However, in the mid- and long-term follow-up periods and according to experimental observations, neurological function ultimately reached the same level as that of non-DM patients, with good control of postoperative blood glucose. One study [ 30 ] reported that preoperative chronic hyperglycaemia is the cause of poor neurological recovery following cervical spinal cord injury in DM patients and that good control of blood glucose after injury can indeed significantly improve outcomes. Our retrospective cohort analysis established HbA1c thresholds as critical determinants of surgical risk stratification and postoperative neurological recovery in diabetic patients undergoing cervical decompression. In patients with HbA1c ≥ 6.5% (irrespective of admission glucose levels), suboptimal short-term neurological outcomes were strongly associated with chronic hyperglycaemia, as evidenced by a mean preoperative HbA1c exceeding 8.0% in the diabetic cohort. This aligns with consensus data indicating HbA1c ≥ 8.0% as a high-risk threshold for increased reoperation rates and compromised recovery following spinal procedures 31 . On the basis of these findings, we propose a tiered management framework: (1) Preoperative glycaemic optimization targeting HbA1c < 8.0% through structured medical intervention, with elective surgery deferral for patients exceeding this threshold until sustained metabolic control is achieved; (2) Implementation of standardized perioperative protocols combining rigorous glycaemic control (HbA1c reduction-focused) and postoperative pharmacotherapy, which in our cohort yielded comparable 6–12 month functional outcomes between diabetic and nondiabetic groups; and (3) recognition of an evidence gap regarding the prognostic significance of HbA1c 6.5–7.9%, necessitating prospective studies to refine intervention thresholds. The obtained data underscore the imperative for HbA1c-driven surgical decision-making while highlighting the need for consensus guidelines on moderate hyperglycaemia management in spinal surgery candidates. Emerging clinical and experimental evidence has demonstrated that DM induces multilevel neurological damage through chronic microangiopathic processes, impairing both central and peripheral nervous system recovery. Retrospective analyses revealed that prolonged hyperglycaemic exposure exacerbates ischaemic neuropathy by compromising the vascular supply of neural tissue, significantly hindering short-term functional recovery post-lumbar surgery (1.65-fold increased reoperation risk) 17 . Pathophysiological mechanisms involve dual issues: microangiopathy-induced hypoperfusion potentiates nerve root vulnerability to compressive injuries 32 , and impaired vascular resilience exacerbates oedema formation during mechanical irritation 21 . Recent advancements in neurovascular mapping using the AAV-BI30 viral vector have enabled precise cerebrovascular endothelial cell transduction, as validated by colocalization with ERG (erythroblastosis transformation specific related gene, endothelial marker) and α-SMA (Alpha Smooth Muscle Actin, pericyte marker) 33 . In this investigation, we will employ advanced microvascular labelling techniques to perform three-dimensional mapping of the cervical spinal cord microvasculature. This approach will enable direct quantitative assessment of diabetes-induced microvascular remodelling while establishing topographic relationships between vascular degeneration and electrophysiologically confirmed neurological deficits. MEP outcomes inherently reflect the integrative conduction capacity of both central and peripheral neural pathways. Diabetes-induced neuropathic damage—whether targeting central motor tracts or peripheral axons—may collectively degrade postoperative motor pathway integrity following cervical decompressive surgery, resulting in electrophysiological performance inferior to that of nondiabetic counterparts. While absolute MEP values alone may not fully delineate functional recovery gradients, our data phenotypically demonstrate systemic neural deterioration in diabetic cohorts. To address this limitation in subsequent investigations, normalized neurophysiological metrics, specifically the MEP amplitude‒to‒maximal muscle‒evoked potential (M‒max) ratio, will be used to disentangle central versus peripheral contributions to conduction deficits. This ratio-based approach aligns with established methodologies for differentiating myelopathic and radicular pathologies, thereby refining prognostic stratification in diabetic spinal surgery patients. Our study includes FLAS, a novel scoring system for quantifying forelimb motor function in rodent models with particular relevance to research on cervical spinal cord injury (SCI). Preservation of forelimb mobility is critical for survival capacity and quality of life in both humans and experimental animals post-SCI. Conventional rodent cervical SCI models predominantly induce severe damage to the dorsal and lateral funiculi and grey matter at the injury epicentre, whereas ventral white matter tracts are relatively preserved. FLAS provides a basis for fine-scale evaluations of both fine motor skills (e.g., digit coordination and targeted grasping) and gross limb movement patterns, demonstrating high reliability and operational feasibility in C5–C7 segmental injury paradigms. However, its capacity to delineate recovery-phase adaptive neuroplasticity—such as corticospinal tract reorganization or compensatory supraspinal recruitment—remains unvalidated, necessitating further investigation 34 . In our C5–C6 posterior midline contusion model, FLAS effectively captures diabetes-associated grey matter pathology, including neuronal loss and microangiopathic degeneration. Nevertheless, this injury paradigm approach incompletely models corticospinal tract dysfunction (ventral white matter integrity), which is essential for evaluating diabetes-induced axonal conduction deficits. Future studies will incorporate lateralized or ventrolateral compression models to assess both grey matter injury and corticospinal tract integrity synergistically, thereby refining the translational importance of diabetic SCI pathophysiology. This study has several limitations. First, there are some inevitable biases due to the retrospective nature of the study, and the patient sample size was small, which limits the strength and extensiveness of the data. Second, DM patients had not pre- and postoperative MEP data available. Third, the specific range of laminectomy for establishing a rat model of cervical spinal cord injury needs to be determined in future studies. In the future, DM patients who undergo cervical spinal cord surgery should be stratified according to the DM course and the level of blood glucose to determine the corresponding effects on postoperative neurological recovery. Further studies are warranted to refine the rat cervical SCI models and optimize the MEP assessment methodology. Conclusions In summary, the integrated findings from retrospective clinical analyses and experimental animal studies collectively indicate that DM may contribute to suboptimal postoperative motor functional recovery following cervical decompressive surgery through hyperglycaemia-induced neuronal necrosis/loss and axonal degeneration. This clinically significant phenomenon warrants in-depth investigation into its underlying patho-mechanisms. Neurosurgeons should perform thorough preoperative evaluations with particular attention to diabetic neuropathy severity in cervical spondylosis patients. For individuals with HbA1c levels ≥ 8.0%, a period of pharmacological intervention targeting strict glycaemic control is strongly recommended prior to surgical intervention. Failure to address these metabolic parameters may predispose patients to postoperative motor dysfunction or de novo neurological deficits. Declarations Author Contribution BGL conceptualized the ideas. PW drafted, and wrote the original manuscript. PW conducted the experiments. BWX collected all the data. BXW, DZ, THR, and BGL revised the manuscript. All the authors have reviewed the manuscript and approved its submission. Funding This work was funded by the National Natural Science Foundation of China (No. 82272524) and the High Level Public Health Technology Talent Construction Project (NO. Leading Talent-02–05). Data Availability The data that support the findings of this study are available from the corresponding author, Professor Baoge Liu, upon reasonable request. Ethics Approval This Clinical retrospective study was conducted according to the guidelines of the Declaration of Helsinki and approved by the Ethical Committee of Beijing Tiantan Hospital, Capital Medical University（KY2022-248-02） with a waiver of written informed consent. All animal experiments were conducted in accordance with the Guidelines for Institutional Animal Care and Use Committee (2024363). The procedures were approved by the Ethics Committee of Beijing Neurosurgical Institute. We reconfirmed our manuscript that the study had adhered to the ARRIVE guidelines. Competing interests The authors declare that they have no competing interests. Disclosure statement No potential conflict of interest was reported by the author(s). Author details 1 Department of Orthopaedic Surgery, Beijing Tiantan Hospital, Capital Medical University, No. 119 South 4th Ring West Road, Fengtai District, Beijing, 100070, China. References Tetreault L, Ibrahim A, Côté P, Singh A, Fehlings MG (2016) A systematic review of clinical and surgical predictors of complications following surgery for degenerative cervical myelopathy. J Neurosurg Spine 24:77–99 Dyck PJ, Norell JE, Dyck PJ (1999) Microvasculitis and ischemia in diabetic lumbosacral radiculoplexus neuropathy. Neurology 53:2113–2121 Liu B, Zhu D, Yang J, Zhang Y, VanHoof T, Okito JPK (2015) Can multilevel anterior cervical discectomy and fusion result in decreased lifting capacity of the shoulder? World Neurosurg 84:1636–1644 Chiba K, Toyama Y, Matsumoto M, Maruiwa H, Watanabe M, Hirabayashi K (2002) Segmental motor paralysis after expansive open-door laminoplasty. Spine 27:2108–2115 Uematsu Y, Tokuhashi Y, Matsuzaki H (1998) Radiculopathy after laminoplasty of the cervical spine. Spine 23:2057–2062 Yonenobu K, Hosono N, Iwasaki M, Asano M, Ono K (1991) Neurologic complications of surgery for cervical compression myelopathy. Spine 16:1277–1282 Kim CH, Chung CK, Shin S, Choi BR, Kim MJ, Park BJ (2015) The relationship between diabetes and the reoperation rate after lumbar spinal surgery: a nationwide cohort study. Spine J 15(1):866–874 Shaw JE, Sicree RA, Zimmet PZ (2010) Global estimates of the prevalence of diabetes for 2010 and 2030. Diabetes Res Clin Pract 87(1):4–14 Epstein NE (2017) Predominantly negative impact of diabetes on spinal surgery: A review and recommendation for better preoperative screening. Surg Neurol Int 8:107 Tesfaye S, Boulton AJM, Dyck PJ, Freeman R, Horowitz M, Kempler P (2010) Diabetic neuropathies: update on definitions, diagnostic criteria, estimation of severity, and treatments. Diabetes Care 33:2285–2293 Dyck PJ, Kratz KM, Karnes JL, Litchy WJ, Klein R, Pach JM (1993) The prevalence by staged severity of various types of diabetic neuropathy, retinopathy, and nephropathy in a population-based cohort: the Rochester diabetic neuropathy study. Neurology 43:817–824 Tesfaye S, Selvarajah D, Gandhi R, Greig M, Shillo P, Fang F (2016) Diabetic peripheral neuropathy may not be as its name suggests. Pain 157:S72–80 Klemencsics I, Lazary A, Szoverfi Z, Bozsodi A, Eltes P, Varga PP (2016) Risk factors for surgical site infection in elective routine degenerative lumbar surgeries. Spine J 16(11):1377–1383 Walid MS, Newman BF, Yelverton JC, Nutter JP, Ajjan, Robinson M (2010) Prevalence of previously unknown elevation of glycosylated hemoglobin in spine surgery patients and impact on length of stay and total cost. J Hosp Med 5(1):E10–E14 Udby PM, Vestergaard T, Ohrt-Nissen S, Carreon LY (2023) The impact of Diabetes in patients with lumbar stenosis - A propensity-score matched study on patient-reported outcomes after surgery. Clin Neurol Neurosurg 235:108038 Silverstein MP, Miller JA, Xiao R, Lubelski D, Benzel EC, Mroz TE (2016) The impact of diabetes upon quality of life outcomes after lumbar decompression. Spine J 16(6):714–721 Lee CH, Kim CH, Chung CK, Choi Y, Kim MJ, Yim D (2020) Long-Term Effect of Diabetes on Reoperation After Lumbar Spinal Surgery: A Nationwide Population-Based Sample Cohort Study. World Neurosurg 139:e439–e448 Anderson KD, Sharp KG, Hofstadter M, Irvine KA, Murray M, Steward O (2009) Forelimb locomotor assessment scale (FLAS): novel assessment of forelimb dysfunction after cervical spinal cord injury. Exp Neurol 220(1):23–33 Armaghani SJ, Archer KR, Rolfe R, Demaio DN, Devin CJ (2016) Diabetes Is Related to Worse Patient-Reported Outcomes at Two Years Following Spine Surgery. J Bone Joint Surg Am 98(1):15–22 Nagata K, Nakamoto H, Sumitani M, Kato S, Yoshida Y, Kawamura N (2021) Diabetes is associated with greater leg pain and worse patient-reported outcomes at 1 year after lumbar spine surgery. Sci Rep 11(1):8142 Takahashi S, Suzuki A, Toyoda H, Terai H, Dohzono S, Yamada K (2013) Characteristics of diabetes associated with poor improvements in clinical outcomes after lumbar spine surgery. Spine (Phila Pa 1976) 38(6):516–522 Wang P, Liu B, Rong T, Wu B (2022) Is diabetes the risk factor for poor neurological recovery after cervical spine surgery? A review of the literature. Eur J Med Res 27(1):263 Massie R, Mauermann ML, Staff NP, Amrami KK, Mandrekar JN, Dyck PJ (2021) Diabetic cervical radiculoplexus neuropathy: a distinct syndrome expanding the spectrum of diabetic radiculoplexus neuropathies. Brain 135(Pt 10):3074–3088 Selvarajah D, Wilkinson ID, Emery CJ, Harris ND, Shaw PJ, Witte DR (2006) Early involvement of the spinal cord in diabetic peripheral neuropathy. Diabetes Care 29(12):2664–2669 Moon TJ, Furdock R, Ahn N (2022) Do Patients with Chronic Diabetes Have Worse Motor Outcomes After Cervical ASIA C Traumatic Spinal Cord Injury? Clin Spine Surg 35(9):E731–E736 Yu Z, Chen C, Yu T, Ye Y, Zheng X, Zhan S (2023) Electrophysiological evidence of diabetes' impacts on central conduction recoveries in degenerative cervical myelopathy after surgery. Eur Spine J 32(6):2101–2109 Jaiswal S, von Brabazon F, Acs LR, Collier D (2022) and Allison, N. Spinal cord injury chronically depresses glucose uptake in the rodent model. Neurosci Lett 771:136416 Stamboulis E, Vassilopoulos D, Kalfakis N (2005) Symptomatic focal mononeuropathies in diabetic patients: increased or not? J Neurol 252(4):448–452 Knopp M, Rajabally YA (2012) Common and less common peripheral nerve disorders associated with diabetes. Curr Diabetes Rev 8(3):229–236 Park KS, Kim JB, Keung M, Seo YJ, Seo SY, Mun SA (2020) Chronic Hyperglycemia before Spinal Cord Injury Increases Inflammatory Reaction and Astrogliosis after Injury: Human and Rat Studies. J Neurotrauma 37(9):1165–1181 Park C, Gottfried ON, Commentary (2021) Preoperative HbA1c > 8% Is Associated With Poor Outcomes in Lumbar Spine Surgery: A Michigan Spine Surgery Improvement Collaborative Study. Neurosurgery 89(6):E308–E309 Park CH, Min KB, Min JY, Kim DH, Seo KM, Kim DK (2021) Strong association of type 2 diabetes with degenerative lumbar spine disorders. Sci Rep 11(1):16472 Krolak T, Chan KY, Kaplan L, Huang Q, Wu J, Zheng Q et al (2022) A High-Efficiency AAV for Endothelial Cell Transduction Throughout the Central Nervous System. Nat Cardiovasc Res 1(4):389–400 Singh A, Krisa L, Frederick KL, Sandrow-Feinberg H, Balasubramanian S, Stackhouse SK et al (2014) Forelimb locomotor rating scale for behavioral assessment of recovery after unilateral cervical spinal cord injury in rats. J Neurosci Methods 226:124–131 Additional Declarations No competing interests reported. Supplementary Files SupplementalTables.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7264091","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":502139804,"identity":"4ca7e03e-3103-412a-8895-a2fb19096709","order_by":0,"name":"Peng Wang","email":"","orcid":"","institution":"Beijing Tiantan Hospital, Capital Medical University","correspondingAuthor":false,"prefix":"","firstName":"Peng","middleName":"","lastName":"Wang","suffix":""},{"id":502139805,"identity":"5783e7ef-60e9-44e8-9108-c7fed9de2316","order_by":1,"name":"Bingxuan Wu","email":"","orcid":"","institution":"Beijing Tiantan Hospital, Capital Medical University","correspondingAuthor":false,"prefix":"","firstName":"Bingxuan","middleName":"","lastName":"Wu","suffix":""},{"id":502139806,"identity":"8894e9cf-99f9-4436-9412-c59dfac5e26d","order_by":2,"name":"Duo Zhang","email":"","orcid":"","institution":"Beijing Tiantan Hospital, Capital Medical University","correspondingAuthor":false,"prefix":"","firstName":"Duo","middleName":"","lastName":"Zhang","suffix":""},{"id":502139807,"identity":"96c33e7c-035f-4a36-a593-4644fe66c27b","order_by":3,"name":"Tianhua Rong","email":"","orcid":"","institution":"Beijing Tiantan Hospital, Capital Medical University","correspondingAuthor":false,"prefix":"","firstName":"Tianhua","middleName":"","lastName":"Rong","suffix":""},{"id":502139808,"identity":"02c7c00c-72bd-4dbb-9e3c-e9bff8e1dbe0","order_by":4,"name":"Bowei Xiao","email":"","orcid":"","institution":"Beijing Tiantan Hospital, Capital Medical University","correspondingAuthor":false,"prefix":"","firstName":"Bowei","middleName":"","lastName":"Xiao","suffix":""},{"id":502139809,"identity":"2d0f8dc4-7c1c-4b12-aafd-51973a51df47","order_by":5,"name":"Baoge Liu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA4ElEQVRIiWNgGAWjYBACAzBZIMHALwFmScgQqcVAgkFyBgNjA1ALD7FagOgGWAsDYS3m7IcPv/hgYJG4+Xbz8Uc3aix4GNgPH92AT4tlT1qa5QwDicRtd44lNuccAzqMJy3tBl6HHcgxM+YBabmRY9icwwbUIsFjhl/L+Tdmxn+AWjbPAGn5R4yWGznGj4EhlrhBAqglt40ILZYznqUx9hhIGM+4kZY4O7dPgoeNkF/M+ZMPf/hRUSfbPyP5wOecb3Vy/OyHj+HVAgRsEqhcAspBgPkDEYpGwSgYBaNgJAMALMxHjtGD1qEAAAAASUVORK5CYII=","orcid":"","institution":"Beijing Tiantan Hospital, Capital Medical University","correspondingAuthor":true,"prefix":"","firstName":"Baoge","middleName":"","lastName":"Liu","suffix":""}],"badges":[],"createdAt":"2025-07-31 16:08:20","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7264091/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7264091/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":89570856,"identity":"b7fc836a-e371-41be-8a88-a5cf6cafa8fe","added_by":"auto","created_at":"2025-08-21 12:08:53","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":90896,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCompare JOA score between groups before and after surgery.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(A) The JOA score, six months after surgery were better in the degenerative cervical spondylosis and non-DM group than in the degenerative cervical spondylosis combined with DM group (\u003cem\u003ep\u003c/em\u003e \u0026lt;0.05). (B) The JOA score, six months after surgery were better in the incomplete cervical spinal cord injury and non-DM group than in the incomplete cervical spinal cord injury combined with DM group (\u003cem\u003ep\u003c/em\u003e \u0026lt;0.05).\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7264091/v1/50aa2eb5bd378fce9991139e.png"},{"id":89570816,"identity":"254e1091-a621-4dff-881a-90c684979f09","added_by":"auto","created_at":"2025-08-21 12:08:51","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":72929,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCompare JOA-RR between groups before and after surgery.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(A) The JOA-RR, six months after surgery were better in the degenerative cervical spondylosis and non-DM group than in the degenerative cervical spondylosis combined with DM group (\u003cem\u003ep\u003c/em\u003e \u0026lt;0.05). (B) The JOA-RR, six months after surgery were better in the incomplete cervical spinal cord injury and non-DM group than in the incomplete cervical spinal cord injury combined with DM group (\u003cem\u003ep\u003c/em\u003e \u0026lt;0.05).\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7264091/v1/61889680283c60916a60a023.png"},{"id":89570863,"identity":"5eb9e508-d1c8-4a4c-8993-1a54649ac36d","added_by":"auto","created_at":"2025-08-21 12:08:54","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":97620,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCompare VAS (N) score between groups before and after surgery.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(A) The VAS (N) score, six months after surgery were better in the degenerative cervical spondylosis and non-DM group than in the degenerative cervical spondylosis combined with DM group (\u003cem\u003ep\u003c/em\u003e \u0026lt;0.05). (B) The VAS (N) score, six months after surgery were better in the incomplete cervical spinal cord injury and non-DM group than in the incomplete cervical spinal cord injury combined with DM group (\u003cem\u003ep\u003c/em\u003e \u0026lt;0.05).\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7264091/v1/eaa9b465a417a46aabf34099.png"},{"id":89570915,"identity":"629a3097-d2ce-409f-9dd0-ef330f4277a5","added_by":"auto","created_at":"2025-08-21 12:08:56","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":91763,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCompare VAS (L) score between groups before and after surgery.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(A) The VAS (L) score, six months after surgery were better in the degenerative cervical spondylosis and non-DM group than in the degenerative cervical spondylosis combined with DM group (\u003cem\u003ep\u003c/em\u003e \u0026lt;0.05). (B) The VAS (L) score, six months after surgery were better in the incomplete cervical spinal cord injury and non-DM group than in the incomplete cervical spinal cord injury combined with DM group (\u003cem\u003ep\u003c/em\u003e \u0026lt;0.05).\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7264091/v1/e6226f405c160a4b185fb16c.png"},{"id":89570824,"identity":"0daf11f8-df8d-45af-b948-aaca4104769e","added_by":"auto","created_at":"2025-08-21 12:08:52","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":93360,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCompare NDI score between groups before and after surgery.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(A) The NDI score, six months after surgery were better in the degenerative cervical spondylosis and non-DM group than in the degenerative cervical spondylosis combined with DM group (\u003cem\u003ep\u003c/em\u003e \u0026lt;0.05). (B) The NDI score, six months after surgery were better in the incomplete cervical spinal cord injury and non-DM group than in the incomplete cervical spinal cord injury combined with DM group (\u003cem\u003ep\u003c/em\u003e \u0026lt;0.05).\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7264091/v1/9b7c48654573f1ff1c514adb.png"},{"id":89570833,"identity":"d628071a-68da-4721-8b8d-d0b1d36845d1","added_by":"auto","created_at":"2025-08-21 12:08:53","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":27071,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe forelimb locomotor assessment scale (FLAS) was used to evaluate the forelimb motor function of the rats.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFLAS evaluated the forelimb motor function of rats on the day of modeling of incomplete cervical spinal cord injury, day 7, day 14 and day 30. After 7 days and 14 days, the score of non-diabetic group was higher than that of diabetic group (\u003cem\u003ep\u003c/em\u003e \u0026lt; 0.05).\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7264091/v1/72d8ea6303741f383e7ad5da.jpg"},{"id":89570854,"identity":"9ae75d64-7e63-4d59-9306-e00d5b500e83","added_by":"auto","created_at":"2025-08-21 12:08:53","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":23449,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eNeurophysiologically examination of the type 2 DM rats after one month of modeling.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eExamination of the type 2 DM rats after one month of modeling showed that, compared with those of Group B, the MEPs of the upper limbs demonstrated increased latency and decreased amplitude, while those of the lower limbs demonstrated longer latencies yet similar amplitudes. Group A, diabetes group; Group B, non-diabetic group\u003c/p\u003e","description":"","filename":"7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7264091/v1/f5591bdfd7de46e0aead6040.jpg"},{"id":89570876,"identity":"8436f79b-3138-44d5-b7bb-cad0aa242f78","added_by":"auto","created_at":"2025-08-21 12:08:55","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":64995,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eNeurophysiologically examination of the incomplete cervical spinal cord injury modeling.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOn the day of incomplete cervical spinal cord injury modeling, the latencies of the MEPs of the upper limbs and lower limbs of the rats in Group A and Group B were similar, and the amplitudes were low; moreover, the amplitudes were significantly lower than those of the uninjured rats in the same group. On days 7 and 14 after modeling, a gradual improvement was observed in the amplitude and latency of the MEPs in both groups of rats, and by day 30 of modeling, the recovery had peaked. Within-group comparisons, however, showed that the amplitude was still smaller than that before the modeling in both groups. Group A, diabetes group; Group B, non-diabetic group.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-7264091/v1/8a243d67ff16380b4c6c52b7.png"},{"id":89571330,"identity":"ad77aba1-35c5-427a-9626-bd7f9c6c8c83","added_by":"auto","created_at":"2025-08-21 12:16:55","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":1194098,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eLight microscopy\u003c/strong\u003e \u003cstrong\u003eexamination.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eUnder light microscopy, in the whole view, DM rats had more severe tissue necrosis and scattering of the central canal (for both the grey matter and white matter), and fewer neurons in the peripheral gray matter than non-DM rats. As indicated by the green arrow on the right ，both diabetic (DM) and non-diabetic (non-DM) groups exhibited preserved integrity of the anterior corticospinal tract (ACST), characterized by identifiable neural fibre cells, suggesting retained functional capacity. Notably, non-DM rats demonstrated longer rostrocaudal projections of ACST fibres compared to DM counterparts. In contrast, the lateral corticospinal tract (LCST) could not be reliably delineated in the examined tissue specimens, precluding further structural or comparative analysis.\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-7264091/v1/eb6680ffe6662d6921682578.png"},{"id":89571332,"identity":"287e780e-afc6-4955-817a-348b0e295326","added_by":"auto","created_at":"2025-08-21 12:16:55","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":1234017,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eLight microscopy\u003c/strong\u003e \u003cstrong\u003eexamination.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(Non-DM group):Light microscopy (50×magnification) of the spinal cord anterior horn reveals abundant motor neurons with preserved morphological integrity (green arrows), minimal glial infiltration (blue arrows). (DM group): At equivalent magnification, the anterior horn displays a marked reduction in motor neuron (green arrows) density compared to the Non-DM group, alongside an increased population of round-shaped glial cells (blue arrows), consistent with reactive gliosis secondary to chronic hyperglycaemic injury.\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-7264091/v1/36a5f41cf6ec6c6c42c6f432.png"},{"id":89570827,"identity":"c9a96222-5d3e-465d-aa5e-3da4f97103b2","added_by":"auto","created_at":"2025-08-21 12:08:52","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":456545,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eHigh-resolution electron microscopy examination.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eHigh-Resolution Electron Microscopy Findings in Anterior Horn Motor Neurons:\u003c/p\u003e\n\u003cp\u003e(A) in DM group, the neurons contained larger amounts of lipofuscin, and mild myelin sheath lamella separation and endoplasmic reticulum swelling were observed; (B) in non-DM group, the boundaries of the neurons were round, the myelin sheath lamella was dense, and the axons were clearly visible. (C) diabetic corticospinal tract and anterior horn axonal regions are also demonstrated axonal injury, myelin sheath delamination.\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-7264091/v1/9fdfa7d649e252f548b0b23f.png"},{"id":89571327,"identity":"629892f0-495e-4d08-aece-7428b90c7166","added_by":"auto","created_at":"2025-08-21 12:16:53","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":499274,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eHigh-resolution electron microscopy examination.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eComparative Analysis of Anterior Horn Motor Neurons (1 Month Post-Incomplete Cervical Spinal Cord Injury): (A) DM rats presented with darker neurons with some areas of lipofuscin, some axonal tissue necrosis; (B) in non-DM rats, a small number of autophagosomes were present in the neurons, and the surrounding axons and myelin sheath were intact.\u003c/p\u003e","description":"","filename":"12.png","url":"https://assets-eu.researchsquare.com/files/rs-7264091/v1/ea2ea7c0ec1b575d81b3bc58.png"},{"id":92899287,"identity":"4e533498-e4f1-4935-8b57-429518f3f332","added_by":"auto","created_at":"2025-10-06 20:46:34","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5125712,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7264091/v1/907a9978-ce41-4d60-a579-58be84cd6862.pdf"},{"id":89570896,"identity":"5e36e4eb-763f-4cfb-ac4c-182f2f683d12","added_by":"auto","created_at":"2025-08-21 12:08:56","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":38295,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementalTables.docx","url":"https://assets-eu.researchsquare.com/files/rs-7264091/v1/2cc5d3d0dafc171c60f53702.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"The effects of diabetes on the recovery of motor nerve function after cervical decompression surgery and associated mechanisms","fulltext":[{"header":"Backgrounds","content":"\u003cp\u003eSome patients with cervical spondylosis experience poor functional nerve recovery after surgery and may even experience paralysis of the innervated area that is not present before surgery; these complications are especially prominent in patients with diabetes mellitus (DM). The main factors that negatively affect the efficacy of cervical surgery include hypertension, advanced age, multisegment decompression and fusion, intraoperative intervertebral space hyperextension, postoperative spinal cord drift, nerve root stretching, and ischaemia‒reperfusion injury \u003csup\u003e[\u003cspan additionalcitationids=\"CR2 CR3 CR4 CR5\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e. Among patients receiving spine surgery, 5\u0026ndash;20% have DM \u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e; however, the effect of DM on surgical results, especially in terms of nerve recovery, is still poorly understood.\u003c/p\u003e\u003cp\u003eDM is caused by insulin deficiency, impairment of certain biological functions, or both. The worldwide prevalence of DM among adults aged 20\u0026ndash;79 years was approximately 285\u0026nbsp;million in 2010 and is expected to increase to 439\u0026nbsp;million by 2030 \u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e. Chronic hyperglycaemia not only causes organ system damage, dysfunction or failure but also has serious effects on the nervous system \u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e. Diabetic peripheral neuropathy, damage to the nerves of the distal limbs, is one of the most common complications of DM \u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e. Moreover, DM can also affect the central nervous system \u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e. Many reports have confirmed that DM is a risk factor for adverse clinical outcomes and an increased incidence of complications after lumbar surgery, including surgical site infection \u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e, prolonged hospitalization and increased hospitalization costs \u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e, poor postoperative neurological recovery \u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e, and increased reoperation rates \u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e. However, studies of the clinical effects and complications of cervical spine surgery in DM patients are scarce.\u003c/p\u003e\u003cp\u003eIn this study, the data for 129 patients who underwent cervical spine surgery at the Department of Orthopaedics, Beijing Tiantan Hospital, Capital Medical University, were retrospectively analysed. Patient age, mean preoperative glycosylated haemoglobin (HbA1c) level, mean preoperative blood glucose level, mean volume of intraoperative bleeding, operative segment, mean hospitalization length of stay, mean hospitalization costs, Japanese Orthopaedic Association (JOA) score, visual analogue scale (VAS) score, JOA recovery rate (JOA-RR), and neck disability index (NDI) for the patients in the DM group were compared with those of individuals in the non-DM group, and the effect of DM on motor nerve function recovery after cervical decompression was evaluated. Moreover, incomplete cervical spinal cord injury was established in type 2 DM rats, and changes in postoperative limb activity, motor-evoked potentials (MEPs), and the number of neurons and changes in the axons and other organelles at the site of injury were analysed to explain the poor motor nerve function recovery following cervical decompression due to pathological changes induced by DM.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cp\u003e\u003cb\u003ePatients\u003c/b\u003e\u003c/p\u003e\u003cp\u003eBetween January 2021 and December 2023, 129 patients who underwent cervical spine surgery at the Department of Orthopaedics, Beijing Tiantan Hospital, Capital Medical University, were included in this study. Patients were included on the basis of the following criteria: (1) the presence of a cervical degenerative disease; (2) incomplete cervical spinal cord injury; and (3) follow-up duration\u0026thinsp;\u0026ge;\u0026thinsp;1 year. Patients were excluded if they met the following criteria: (1) had type 1 DM; (2) long-term use of steroids; (3) had cervical spinal cord injury or cervical spondylosis supported by imaging studies but lacking symptoms of clinical nerve injury; (4) had complete cervical spinal cord injury; (5) had a cervical tumour or infection; (6) had cervical revision; or (7) had incomplete medical records. According to the type of cervical spondylosis and the presence of DM before surgery (Chinese Diabetes Guidelines 2024, regarding diagnostic thresholds: (1) typical symptoms of diabetes; (2) random plasma glucose\u0026thinsp;\u0026ge;\u0026thinsp;11.1 mmol/L; and (3) fasting plasma glucose\u0026thinsp;\u0026ge;\u0026thinsp;7.0 mmol/L or HbA1c\u0026thinsp;\u0026ge;\u0026thinsp;6.5%), patients were divided into a degenerative cervical spondylosis combined with DM group (Group A, n\u0026thinsp;=\u0026thinsp;51), a degenerative cervical spondylosis and non-DM group (Group B, n\u0026thinsp;=\u0026thinsp;53), an incomplete cervical spinal cord injury combined with DM group (Group C, n\u0026thinsp;=\u0026thinsp;7), and an incomplete cervical spinal cord injury and non-DM group (Group D, n\u0026thinsp;=\u0026thinsp;18). The study was approved by the Ethical Committee of Beijing Tiantan Hospital, Capital Medical University (KY2022-248-02).\u003c/p\u003e\u003cp\u003e\u003cb\u003eSurgical techniques\u003c/b\u003e\u003c/p\u003e\u003cp\u003eAll surgeries were performed by the same experienced surgeon. The surgical methods included anterior cervical canal decompression, anterior cervical discectomy and fusion (ACDF), anterior cervical corpectomy/fusion (ACCF), posterior cervical single-door laminoplasty, and posterior cervical laminectomy.\u003c/p\u003e\u003cp\u003e\u003cb\u003eEvaluation of neurological function\u003c/b\u003e\u003c/p\u003e\u003cp\u003eA comprehensive neurological examination was performed before the operation and at 1 month, 6 months, 1 year, and 2 years after surgery, during which the NDI score, JOA score, and JOA-RR were used to quantify the degree of neurological deficit, and the VAS score was used to assess the degrees of cervical pain (VAS neck (VAS (N)) score) and limb pain (VAS limbs (VAS (L)) score).\u003c/p\u003e\u003cp\u003eThe JOA-RR formula was as follows: (total postoperative score - total preoperative score)/ (17 - total preoperative score) \u0026times; 100%.\u003c/p\u003e\u003cp\u003e\u003cb\u003eAnimal preparation\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe animal experiments were performed at the Animal Laboratory of the Beijing Neurosurgical Institute. The study protocol was approved by the Ethics Committee of Beijing Neurosurgical Institute (ethics number: 2024363). All animal experiments were conducted in accordance with the Guidelines for the Institutional Animal Care and Use Committee.\u003c/p\u003e\u003cp\u003eFifty adult male SPF-grade Sprague\u0026ndash;Dawley (SD) rats (weighing approximately 200 g) were purchased from Jinan Pengyue Experimental Animal Breeding Co., Ltd. All the animals were evenly divided into 2 groups (Group A and Group B), with 25 rats in each group. The rats in Group A were given ear tags numbered 1\u0026ndash;25, and those in Group B were given ear tags numbered 26\u0026ndash;50.\u003c/p\u003e\u003cp\u003e\u003cb\u003eType 2 DM rat model\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe rats in Group A were fed high-sugar, high-fat, semisynthetic high-calorie feed (D12451; 15% lard, 20% sucrose, 10% egg yolk powder, 1% cholesterol, 0.2% cholate and conventional feed) purchased from Xiaoshu Youtai (Beijing) Biotechnology Co., Ltd. The Group A rats were fed to induce insulin resistance, whereas Group B rats were fed conventional feed. Following a 2-week acclimatisation period, the rats were fasted (with ad libitum access to water) for 18 hours. Group A (diabetic cohort) received a single intraperitoneal injection of streptozotocin (STZ; 35 mg/kg). Blood glucose levels were measured via tail vein sampling at 72 hours post-injection and subsequently twice weekly. Diabetes induction was confirmed if random glucose levels were \u0026ge;\u0026thinsp;11.1 mmol/L and fasting glucose levels were \u0026ge;\u0026thinsp;7.0 mmol/L. Nonresponsive rats underwent repeat STZ administration after a 3-day observation period. When rats with blood glucose\u0026thinsp;\u0026ge;\u0026thinsp;22 mmol/L accompanied by behavioural abnormalities (altered respiration or consciousness) received Novolin N, 3 IU/day subcutaneously for 3\u0026ndash;5 days, glucose levels between 11.1\u0026ndash;20 mmol/L were maintained. The Group A rats were provided unrestricted food/water with daily bedding replacement.\u003c/p\u003e\u003cp\u003e\u003cb\u003eModelling of incomplete cervical spinal cord injury\u003c/b\u003e\u003c/p\u003e\u003cp\u003eSurgical modelling was performed for Groups A and B rats. After the rats were anaesthetized via intraperitoneal injections of pentobarbital sodium (30 mg/kg), they were fixed in the prone position on the operating table, the limbs were immobilized, the hair from the cervical spine was removed, and the lower cervical spine was slightly elevated with gauze and a cotton pad. The tongue was pulled out of the mouth to avoid suffocation. The skin and subcutaneous tissue were incised with a scalpel. Then, the spinous processes and some muscles around the lamina were isolated, after which the C5-C6 spinous processes and part of the lamina were exposed and removed to expose the cervical spinal cord. A modified Allen technique was used to induce incomplete spinal cord injury; specifically, a 20 g Kirschner wire with a diameter of 4 mm was dropped from a height of 3.5 cm through a hollow tube to injure the cervical spinal cord in the area exposed at C5-C6. The establishment of the rat cervical spinal cord injury model was confirmed after congestion appeared at the site of injury, and the rat experienced shaking of the hind limbs or all four limbs and spasmodic swing of the tail. Antibiotic irrigation solution and normal saline were used to rinse the wound, after which the wound was closed. After the rats woke, the animals were administered the analgesic buprenorphine (0.05 mg/kg). The rats were kept in separate cages and given free access to water and food under a 12-hour light/dark cycle. The room was well ventilated and maintained at a temperature of approximately 26\u0026deg;C and 30%-60% humidity. The rats were encouraged to eat daily, and their bladder was compressed 3 times a day until spontaneous urination was restored.\u003c/p\u003e\u003cp\u003e\u003cb\u003eBehavioural assessment\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe forelimb locomotor assessment scale (FLAS) \u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e was used to evaluate the forelimb motor function of the rats in Groups A and B on the day of the operation and 7, 14, and 30 days after incomplete cervical spinal cord injury.\u003c/p\u003e\u003cp\u003e\u003cb\u003eMotor-evoked potential\u003c/b\u003e\u003c/p\u003e\u003cp\u003eAt postoperative days 0 (model establishment), 7, 14, and 30, four randomly selected rats per group were anaesthetized via intraperitoneal injection of pentobarbital sodium (30 mg/kg) and subjected to neurophysiological assessments. MEP recordings were acquired using needle electrodes under standardised conditions: the animals were positioned in lateral recumbency, with biparietal stimulating electrodes placed on the cranial vertex and recording electrodes positioned over the bottom of the biceps brachii or gastrocnemius muscles. The stimulation consisted of dual 10-mV pulses delivered at 0.1\u0026ndash;1 Hz, with the intensity adjusted to elicit observable muscle contraction in the target muscles. The signals were amplified, filtered, and recorded using electromyography. To ensure protocol standardization, triplicate measurements were performed per session with 3-minute intervals between trials. Optimal waveforms were selected on the basis of the shortest latency and highest amplitude, with a mean maximum stimulation current of 26 mA applied across all sessions.\u003c/p\u003e\u003cp\u003e\u003cb\u003eTissue processing, storage and observation methods\u003c/b\u003e\u003c/p\u003e\u003cp\u003eAfter MEP induction and recording, the rats were euthanized with an overdose of pentobarbital sodium (50 mg/kg), after which the spinal cord at the surgical site was quickly removed, opened longitudinally and soaked in 2.5% glutaraldehyde fixative solution at room temperature. After 1 h, the spinal cord was stored at 4\u0026deg;C overnight, washed, dehydrated, embedded in paraffin, sectioned at a thickness of 5 \u0026micro;m, and stained with haematoxylin‒eosin (HE) for observation under an upright light microscope. Another part of the spinal cord from the same rat was subjected to the same procedure as described above until washing, where it was fixed in osmic acid, infiltrated with ethylene oxide, and embedded in resin. The spinal cord was cut into 70-nm-thick cross-sections, which were then stained with 2% uranyl acetate solution and lead citrate staining solution. The sections were assessed via transmission electron microscopy (TEM).\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eSPSS 27.0 software was used for data analysis, and a two-sided \u003cem\u003ep\u003c/em\u003e value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 indicated statistical significance. The measurement data wee expressed as medians, minimum and maximum values, effective numbers of cases, and means\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviations. The counting data are presented as percentages. The Kolmogorov‒Smirnov method (with a sample size greater than 50) and the Shapiro‒Wilk method (with a sample size less than 50) were used to test the normality of the samples. Intergroup comparisons were performed with the independent samples t test for normally distributed data, the rank sum test (Mann‒Whitney U test or Wilcoxon rank sum test) for nonnormally distributed data, and the χ2 test or Fisher's exact test for count data. GraphPad Prism 8.0.2 software was used to create charts. The risk factors for poor neurological recovery after cervical surgery were analysed using univariate and multivariate linear regression models.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cb\u003eClinical characteristics\u003c/b\u003e\u003c/p\u003e\u003cp\u003eA total of 129 patients with cervical spondylosis were analysed, including 59 patients in the DM group and 70 patients in the non-DM group. The clinical characteristics of the patients are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The median age, preoperative mean HbA1c level, mean preoperative blood glucose level, and mean intraoperative blood loss in the degenerative cervical spondylosis combined with DM group were greater than those in the corresponding non-DM group (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05), and the preoperative mean HbA1c level, mean preoperative blood glucose level, mean intraoperative blood loss, mean length of hospitalization stay, and mean hospitalization costs in the incomplete cervical spinal cord injury combined with DM group were greater than those in the corresponding non-DM group (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eClinical Characteristics of patients\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"10\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDM\u003c/p\u003e\u003cp\u003e(N\u0026thinsp;=\u0026thinsp;59)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNon-DM\u003c/p\u003e\u003cp\u003e(N\u0026thinsp;=\u0026thinsp;70)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eGroup A\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;51)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eGroup B\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;53)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003ep\u003c/em\u003e (A vs B)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eGroup C\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;8)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eGroup D\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;17)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u003cem\u003ep\u003c/em\u003e (C vs D)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e63 (34\u0026ndash;79)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e56 (24\u0026ndash;77)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e64 (34\u0026ndash;79)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e57 (39\u0026ndash;76)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e58 (38\u0026ndash;75)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e55 (24\u0026ndash;77)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e0.440\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGender\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.833\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.812\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e0.726\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003emale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e36\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e44\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e31 (60.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e31 (58.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e5 (62.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e13 (76.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003efemale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e20 (39.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e22 (41.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e3 (37.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e4 (23.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGlycohemoglobin\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e8.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e5.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e8.5\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e5.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e\u003cb\u003e0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBlood glucose\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7.9\u0026thinsp;\u0026plusmn;\u0026thinsp;2.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e7.7\u0026thinsp;\u0026plusmn;\u0026thinsp;2.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e5.0\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e8.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e5.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e\u003cb\u003e0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHospitalization day\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e14.0\u0026thinsp;\u0026plusmn;\u0026thinsp;6.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10.8\u0026thinsp;\u0026plusmn;\u0026thinsp;3.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e13 (5\u0026ndash;34)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e12 (5\u0026ndash;21)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.127\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e13 (8\u0026ndash;40)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e7 (4\u0026ndash;11)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e\u003cb\u003e0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHospitalization expenses\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e96316.1\u0026thinsp;\u0026plusmn;\u0026thinsp;35670.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e86375.4\u0026thinsp;\u0026plusmn;\u0026thinsp;23313.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.060\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e93903.7\u0026thinsp;\u0026plusmn;\u0026thinsp;33979.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e92436.0\u0026thinsp;\u0026plusmn;\u0026thinsp;21605.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.793\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e111393.2\u0026thinsp;\u0026plusmn;\u0026thinsp;44461.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e67480.7\u0026thinsp;\u0026plusmn;\u0026thinsp;18049.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e\u003cb\u003e0.002\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePeroperative bleeding\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e54.9\u0026thinsp;\u0026plusmn;\u0026thinsp;37.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e35.5\u0026thinsp;\u0026plusmn;\u0026thinsp;18.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e45(10\u0026ndash;500)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e30(10\u0026ndash;100)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e0.002\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e80 (50\u0026ndash;500)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e40(20\u0026ndash;100)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e\u003cb\u003e0.005\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOperative segment\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3 (1\u0026ndash;4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2 (1\u0026ndash;4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.170\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3 (1\u0026ndash;4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e2 (1\u0026ndash;3)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e0.041\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1 (1\u0026ndash;2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e2 (1\u0026ndash;4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e0.087\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"10\"\u003eDM, diabetes mellitus. Group A, degenerative cervical spondylosis combined with DM group. Group B, degenerative cervical spondylosis and non-DM group. Group C, incomplete cervical spinal cord injury combined with DM group. Group D, incomplete cervical spinal cord injury and non-DM group.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003ePostoperative neurological recovery\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe JOA score, JOA-RR, NDI, VAS (N) score, and VAS (L) score of all patients before surgery and at 1 month, 3 months, 6 months, 1 year, and 2 years after the operation were recorded. The JOA score, JOA-RR, NDI, VAS (N) score, and VAS (L) score improved 1 month after surgery relative to the preoperative values for each of the four groups (Supplementary Tables\u0026nbsp;1\u0026ndash;4). Regardless of the type of cervical spine disease, the JOA score, JOA-RR, NDI, VAS (N) score, and VAS (L) score six months after surgery were better in the non-DM group than in the DM group (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, Supplementary Table\u0026nbsp;5\u0026ndash;9). Preoperative HbA1c level, age, intraoperative blood loss, surgical segment, and preoperative blood glucose level were identified as significant predictors of poor outcomes in the univariable linear regression analyses. Subsequent multivariable linear regression indicated that age and preoperative HbA1c were independent predictors of postoperative JOA (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.209, △R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.194, F\u0026thinsp;=\u0026thinsp;13.36, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01), the preoperative blood glucose level was an independent predictor of postoperative NDI (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.088, △R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.079, F\u0026thinsp;=\u0026thinsp;9.788, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01), and the surgical segment and preoperative blood glucose level were independent predictors of the postoperative VAS (L) score (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.168, △R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.151, F\u0026thinsp;=\u0026thinsp;10.171, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMultiple Linear Regression Analysis of JOA\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eitem\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eB\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eS.E.\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eβ\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003et value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGlycohemoglobin\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026minus;\u0026thinsp;.330\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e.094\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026minus;\u0026thinsp;.312\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e-3.511\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e.001\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026minus;\u0026thinsp;.063\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e.019\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026minus;\u0026thinsp;.303\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e-3.399\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e.001\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003eY\u0026thinsp;=\u0026thinsp;21.16\u0026ndash;0.33\u0026times; preoperative HbA1c level \u0026minus;\u0026thinsp;0.063\u0026times; age (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.209, △R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.194, F\u0026thinsp;=\u0026thinsp;13.36, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01)\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMultiple Linear Regression Analysis of NDI\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eitem\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eB\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eS.E.\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eβ\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003et value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBlood glucose\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.999\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e.319\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.296\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3.129\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e.002\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003eY\u0026thinsp;=\u0026thinsp;2.774\u0026thinsp;+\u0026thinsp;0.999\u0026times; blood glucose (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.088, △R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.079, F\u0026thinsp;=\u0026thinsp;9.788, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01)\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMultiple Linear Regression Analysis of VAS(L)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eitem\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eB\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eS.E.\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eβ\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003et value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBlood glucose\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e.315\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e.075\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.403\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e4.355\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOperative segment\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026minus;\u0026thinsp;.432\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e.216\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026minus;\u0026thinsp;.185\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e-2.000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e.048\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003eY\u0026thinsp;=\u0026thinsp;0.716\u0026thinsp;+\u0026thinsp;0.315\u0026times; blood glucose \u0026minus;\u0026thinsp;0.432\u0026times; operative segment (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.168, △R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.151, F\u0026thinsp;=\u0026thinsp;10.171, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01)\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eSuccessful modelling of type 2 DM rats\u003c/b\u003e\u003c/p\u003e\u003cp\u003eOne week and one month after STZ injection, the rats in Group A presented significant polydipsia, polyphagia, polyuria, and weight loss. The measurement of random blood glucose from the tail vein yielded a 100% success rate for establishing rat models of type 2 DM, as confirmed by sustained hyperglycaemia. The blood glucose levels of individuals in Group A after one month were greater than those of individuals in Group B (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05), whereas the body weights were lower in Group A than Group B (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eBlood glucose and weight of rats\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBlood glucose and weight\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGroup A\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eGroup B\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eModeling 1-week of random blood glucose values\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e18.99\u0026thinsp;\u0026plusmn;\u0026thinsp;2.89\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e7.98\u0026thinsp;\u0026plusmn;\u0026thinsp;1.73\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;0.001\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eModeling 1-month of random blood glucose values\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e16.11\u0026thinsp;\u0026plusmn;\u0026thinsp;2.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e7.30\u0026thinsp;\u0026plusmn;\u0026thinsp;1.70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;0.001\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eModeling 1-month of weight\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e468.55\u0026thinsp;\u0026plusmn;\u0026thinsp;64.41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e667.44\u0026thinsp;\u0026plusmn;\u0026thinsp;30.92\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;0.001\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eA B\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eBehavioural results\u003c/b\u003e\u003c/p\u003e\u003cp\u003eDuring the modelling of incomplete cervical spinal cord injury, most of the rats in the two groups exhibited tetraplegia, were unable to walk and could only raise their heads, whereas a small number of the rats in Groups A and B exhibited slight flexion of the elbow and shoulder joints. Moreover, there was no significant difference in the FLAS score (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05) between the two groups. After 7 days, the rats in the two groups could stand on their limbs, but their wrist and grip strength were poor when eating, and the FLAS score of Group B was higher than that of Group A (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.036). After 14 days, the rats in the two groups moved around freely. However, a few rats in the two groups still displayed poor grasping ability; the FLAS score of Group B was higher than that of Group A (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.043). After 30 days, the rats in the two groups were able to move freely, suggesting that their motor function had essentially recovered. The grip strength of one rat in Group A did not recover, however, and it needed assistance maintaining its head when eating. There was no significant difference in the FLAS score between the two groups at 30 days (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cb\u003eSomatic MEPs\u003c/b\u003e\u003c/p\u003e\u003cp\u003eCompared with Group B, Group A demonstrated prolonged latency and reduced amplitude in both the upper and lower limbs at 1 month post-modelling, although the amplitude reduction in the lower limbs was less pronounced than that in the upper limbs. (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e). On the day of incomplete cervical spinal cord injury modelling, the latencies of the MEPs of the upper limbs and lower limbs of the rats in Group A and Group B were similar, and the amplitudes were low; moreover, the amplitudes were significantly lower than those of the uninjured rats in the same group. On days 7 and 14 after modelling, a gradual improvement was observed in the amplitude and latency of the MEPs in both groups of rats, and by day 30 of modelling, the recovery had peaked. However, within-group comparisons revealed that the amplitude was still smaller than that before modelling in both groups (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cb\u003eHistological observation\u003c/b\u003e\u003c/p\u003e\u003cp\u003eDuring the establishment of the rat model of incomplete cervical spinal cord injury, the sites of injury in Groups A and B were observed via light microscopy. The area surrounding the injury site revealed tissue necrosis, which was more severe in the white matter than in the grey matter, as well as vascular proliferation and loss of neurons. Despite the same degree of injury, Group A rats presented more severe tissue necrosis and scattering of the central canal (for both the grey matter and white matter) and fewer neurons in the peripheral grey matter than Group B rats did. A small number of neurons and some axonal tissues could still be observed in Group B. In the 50\u0026times; magnified histological sections, both groups A and B exhibited discernible anatomical architecture and trajectories of the anterior corticospinal tracts, containing abundant nerve fibre cells\u0026mdash;a histological manifestation indicative of preserved conductive functionality in both cohorts. However, comparative analysis revealed that group B demonstrated superior structural integrity for these neural pathways, as evidenced by more coherent axonal cell arrangement (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e). One month after the modelling began, a large amount of gliosis was observed in the area surrounding the injury site in the two groups. Under 50\u0026times; microscopic examination, histological analysis of the anterior horn regions of the spine revealed distinct intergroup variations: Group A demonstrated a significant reduction in motor neuron density accompanied by an abundance of rounded glial cells, with the axonal architecture of residual motor neurons being non-discernible. In contrast, Group B exhibited well-preserved motor neuron populations with intact morphological characteristics coupled with minimal glial cell infiltration. These observations were substantiated by quantitative histomorphometric assessments and ultrastructural validation protocols (Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eHigh-resolution electron microscopy revealed that, 1 month after the establishment of the type 2 DM rat model, in Group A, the anterior horn motor neurons contained larger amounts of lipofuscin, and mild myelin sheath lamella separation and endoplasmic reticulum swelling were observed; in Group B, the boundaries of the anterior horn motor neurons were round, the myelin sheath lamella was dense, and the axons were clearly visible (Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003eA-B). The corticospinal tract‒anterior horn interface of Group A rats also exhibited axonal injury, myelin sheath delamination, breakage, and dispersion, and severe internal axonal tissue swelling caused by typical hyperglycaemic factors was observed (Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003eC). Comparative analysis of anterior horn motor neurons (1 month post-incomplete cervical spinal cord injury), Group A rats presented darker neurons with some areas of lipofuscin, some axonal tissue necrosis, persistence of separated and fractured axonal lamellae, and preservation of the internal axonal structure and function. In Group B, a small number of autophagosomes were present in the neurons, and the surrounding axons and myelin sheath were intact (Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eDM is one of the most common comorbidities among patients who undergo cervical spinal cord surgery. Studies have shown that neurological recovery in DM patients is poor following spine surgery, especially lumbar surgery \u003csup\u003e[\u003cspan additionalcitationids=\"CR20\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e, primarily due to peripheral nerve microangiopathy and axonal demyelination \u003csup\u003e[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e. These pathological changes have a significant impact on peripheral sensory nerves, yet few studies have investigated their effects on motor nerves. Studies have reported that the effect of DM on peripheral nerves is not limited to the lower extremities but also includes the peripheral nerves of the upper extremities; this effect is referred to as diabetic radiculoplexus neuropathy (DRPN) \u003csup\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/sup\u003e. At the level of the cervical spinal cord, a significantly smaller cross-sectional area can be observed in the early stage of diabetic neuropathy than in healthy individuals \u003csup\u003e[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eIn this study, during the 2-year follow-up of 129 patients who received cervical spinal cord surgery, the recovery rates of sensory and motor nerve function after surgery in DM patients were worse than those in non-DM patients, regardless of the form of injury (i.e., cervical degenerative disease versus incomplete cervical spinal cord injury surgery), particularly among patients with preoperative diabetic neuropathy. Most indicators improved within 6 months after surgery; however, at one year after surgery, the VAS (N) score and the NDI of the incomplete cervical spinal cord injury DM and non-DM groups (Group C vs. Group D) still differed. Multivariate regression analysis revealed that a high preoperative HbA1c level was correlated with a low postoperative JOA score, whereas the preoperative blood glucose level was positively associated with the postoperative NDI and VAS(L). These results suggest that long-term preoperative blood glucose status and preoperative blood glucose control are both important. This study revealed that the indicators of recovery for individuals in the incomplete cervical spinal cord injury combined with DM group were lower than those of individuals in the cervical degenerative disease combined with DM group. This may be related to the fact that in a long-term hyperglycaemic environment, the resistance of the tissues of the peripheral nerves and spinal cord to injury weakens. A retrospective study \u003csup\u003e[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/sup\u003e revealed that DM patients are not as capable of exercising and require greater wheelchair use one year after cervical spinal cord injury, which is similar to the results of this study.\u003c/p\u003e\u003cp\u003eIn this research, animal experiments were used to explain and validate the observed clinical results. At the same injury strength, one month after cervical spinal cord surgery, the amplitude of the MEPs was lower and the latency was longer in the DM group than in the normal group. This study is the first to use electrophysiological examinations via an animal model to demonstrate that DM can impede the recovery of central nervous system function after cervical decompression. One study \u003csup\u003e[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]\u003c/sup\u003e revealed that, through electrophysiological examination after cervical spine surgery, DM was an independent risk factor for poor central nerve conduction after cervical decompression, and the surgical efficacy in patients who were insulin dependent for more than 10 years was poor. Under light microscopy, the rats in the DM group presented a larger cervical spinal cord injury area, fewer neurons in the field of view, and a more inconsistent morphology than did the rats in the healthy group. One month after incomplete injury, more glial cells populated the spinal cord of the rats in the DM group, further affecting neuronal conduction. Under electron microscopy, the dispersion of the lamellae was more severe, and the structures in the axons showed more obvious damage in the DM group, both of which can lead to demyelination of myelinated nerve fibres, indicating that DM also substantially affects the spinal cord through microangiopathy and axonal demyelinating lesions. Studies have shown \u003csup\u003e[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]\u003c/sup\u003e that in rats with incomplete cervical spinal cord injury, the spinal cord tends to display decreased glucose uptake, decreased neuronal cell viability, and significantly increased glial cell activation within 28\u0026ndash;90 days after injury. This trend is amplified in DM rats because of the presence of perineural microvasculitis and vascular injury.\u003c/p\u003e\u003cp\u003eIn our experimental paradigm, equivalent current intensity stimulation revealed distinct MEP amplitude patterns between groups. The control rats (Group B) presented lower mean MEP amplitudes in the hindlimbs than in the forelimbs, whereas the diabetic rats (Group A) presented generalized amplitude reductions across all limbs. Notably, the magnitude of hindlimb amplitude reduction in Group A was less pronounced than that observed in the forelimbs than that observed for Group B. Two pathophysiological mechanisms may explain these findings: 1. Neuroanatomical vulnerability: The corticospinal tracts of the innervating hindlimbs reside in the anterolateral and lateral spinal cord regions. Mechanical forces originating from the posterior midline predominantly compromise the dorsomedial tracts governing forelimb function, rendering them susceptible to injury. 2. Electrophysiological correlations: MEP latency prolongation reflects demyelinating pathologies characteristic of diabetic microangiopathy, whereas amplitude reduction is correlated with α-motor neuron depletion and corticospinal conduction integrity. Post-cervical injury, forelimb motor deficits manifest most prominently because of this anatomical‒functional hierarchy. These experimental observations align with those of clinical MEP studies in patients with cervical spinal cord injury. Even at supramaximal stimulation intensities, healthy controls maintain lower baseline hindlimb than forelimbs MEP amplitudes. Injured patients exhibit amplitude reductions across all extremities, yet hindlimb values remain closer to normative ranges than forelimb measurements do, reinforcing the neurotopographical vulnerability gradient.\u003c/p\u003e\u003cp\u003eFor patients with cervical spondylosis combined with DM, cervical surgery for decompressing the nerve is crucial. For these patients, the surgeon should take care to determine the presence of a \u0026ldquo;double compression\u0026rdquo; effect \u003csup\u003e[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e; that is, in addition to the reduced motor and sensory ability of the upper limbs caused by cervical spondylosis, symptoms caused by the entrapment of nerves through other areas of stenosis in the upper limbs are often present. These effects are most likely to occur in DM patients, even in those with early-stage DM \u003csup\u003e[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]\u003c/sup\u003e. This study confirmed that in both DM patients and rats, nerve function recovery following cervical decompression was slow. However, in the mid- and long-term follow-up periods and according to experimental observations, neurological function ultimately reached the same level as that of non-DM patients, with good control of postoperative blood glucose. One study \u003csup\u003e[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/sup\u003e reported that preoperative chronic hyperglycaemia is the cause of poor neurological recovery following cervical spinal cord injury in DM patients and that good control of blood glucose after injury can indeed significantly improve outcomes.\u003c/p\u003e\u003cp\u003eOur retrospective cohort analysis established HbA1c thresholds as critical determinants of surgical risk stratification and postoperative neurological recovery in diabetic patients undergoing cervical decompression. In patients with HbA1c\u0026thinsp;\u0026ge;\u0026thinsp;6.5% (irrespective of admission glucose levels), suboptimal short-term neurological outcomes were strongly associated with chronic hyperglycaemia, as evidenced by a mean preoperative HbA1c exceeding 8.0% in the diabetic cohort. This aligns with consensus data indicating HbA1c\u0026thinsp;\u0026ge;\u0026thinsp;8.0% as a high-risk threshold for increased reoperation rates and compromised recovery following spinal procedures \u003csup\u003e31\u003c/sup\u003e. On the basis of these findings, we propose a tiered management framework: (1) Preoperative glycaemic optimization targeting HbA1c\u0026thinsp;\u0026lt;\u0026thinsp;8.0% through structured medical intervention, with elective surgery deferral for patients exceeding this threshold until sustained metabolic control is achieved; (2) Implementation of standardized perioperative protocols combining rigorous glycaemic control (HbA1c reduction-focused) and postoperative pharmacotherapy, which in our cohort yielded comparable 6\u0026ndash;12 month functional outcomes between diabetic and nondiabetic groups; and (3) recognition of an evidence gap regarding the prognostic significance of HbA1c 6.5\u0026ndash;7.9%, necessitating prospective studies to refine intervention thresholds. The obtained data underscore the imperative for HbA1c-driven surgical decision-making while highlighting the need for consensus guidelines on moderate hyperglycaemia management in spinal surgery candidates.\u003c/p\u003e\u003cp\u003eEmerging clinical and experimental evidence has demonstrated that DM induces multilevel neurological damage through chronic microangiopathic processes, impairing both central and peripheral nervous system recovery. Retrospective analyses revealed that prolonged hyperglycaemic exposure exacerbates ischaemic neuropathy by compromising the vascular supply of neural tissue, significantly hindering short-term functional recovery post-lumbar surgery (1.65-fold increased reoperation risk) \u003csup\u003e17\u003c/sup\u003e. Pathophysiological mechanisms involve dual issues: microangiopathy-induced hypoperfusion potentiates nerve root vulnerability to compressive injuries\u003csup\u003e32\u003c/sup\u003e, and impaired vascular resilience exacerbates oedema formation during mechanical irritation\u003csup\u003e21\u003c/sup\u003e. Recent advancements in neurovascular mapping using the AAV-BI30 viral vector have enabled precise cerebrovascular endothelial cell transduction, as validated by colocalization with ERG (erythroblastosis transformation specific related gene, endothelial marker) and α-SMA (Alpha Smooth Muscle Actin, pericyte marker) \u003csup\u003e33\u003c/sup\u003e. In this investigation, we will employ advanced microvascular labelling techniques to perform three-dimensional mapping of the cervical spinal cord microvasculature. This approach will enable direct quantitative assessment of diabetes-induced microvascular remodelling while establishing topographic relationships between vascular degeneration and electrophysiologically confirmed neurological deficits. MEP outcomes inherently reflect the integrative conduction capacity of both central and peripheral neural pathways. Diabetes-induced neuropathic damage\u0026mdash;whether targeting central motor tracts or peripheral axons\u0026mdash;may collectively degrade postoperative motor pathway integrity following cervical decompressive surgery, resulting in electrophysiological performance inferior to that of nondiabetic counterparts. While absolute MEP values alone may not fully delineate functional recovery gradients, our data phenotypically demonstrate systemic neural deterioration in diabetic cohorts. To address this limitation in subsequent investigations, normalized neurophysiological metrics, specifically the MEP amplitude‒to‒maximal muscle‒evoked potential (M‒max) ratio, will be used to disentangle central versus peripheral contributions to conduction deficits. This ratio-based approach aligns with established methodologies for differentiating myelopathic and radicular pathologies, thereby refining prognostic stratification in diabetic spinal surgery patients.\u003c/p\u003e\u003cp\u003eOur study includes FLAS, a novel scoring system for quantifying forelimb motor function in rodent models with particular relevance to research on cervical spinal cord injury (SCI). Preservation of forelimb mobility is critical for survival capacity and quality of life in both humans and experimental animals post-SCI. Conventional rodent cervical SCI models predominantly induce severe damage to the dorsal and lateral funiculi and grey matter at the injury epicentre, whereas ventral white matter tracts are relatively preserved. FLAS provides a basis for fine-scale evaluations of both fine motor skills (e.g., digit coordination and targeted grasping) and gross limb movement patterns, demonstrating high reliability and operational feasibility in C5\u0026ndash;C7 segmental injury paradigms. However, its capacity to delineate recovery-phase adaptive neuroplasticity\u0026mdash;such as corticospinal tract reorganization or compensatory supraspinal recruitment\u0026mdash;remains unvalidated, necessitating further investigation\u003csup\u003e34\u003c/sup\u003e. In our C5\u0026ndash;C6 posterior midline contusion model, FLAS effectively captures diabetes-associated grey matter pathology, including neuronal loss and microangiopathic degeneration. Nevertheless, this injury paradigm approach incompletely models corticospinal tract dysfunction (ventral white matter integrity), which is essential for evaluating diabetes-induced axonal conduction deficits. Future studies will incorporate lateralized or ventrolateral compression models to assess both grey matter injury and corticospinal tract integrity synergistically, thereby refining the translational importance of diabetic SCI pathophysiology.\u003c/p\u003e\u003cp\u003eThis study has several limitations. First, there are some inevitable biases due to the retrospective nature of the study, and the patient sample size was small, which limits the strength and extensiveness of the data. Second, DM patients had not pre- and postoperative MEP data available. Third, the specific range of laminectomy for establishing a rat model of cervical spinal cord injury needs to be determined in future studies. In the future, DM patients who undergo cervical spinal cord surgery should be stratified according to the DM course and the level of blood glucose to determine the corresponding effects on postoperative neurological recovery. Further studies are warranted to refine the rat cervical SCI models and optimize the MEP assessment methodology.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn summary, the integrated findings from retrospective clinical analyses and experimental animal studies collectively indicate that DM may contribute to suboptimal postoperative motor functional recovery following cervical decompressive surgery through hyperglycaemia-induced neuronal necrosis/loss and axonal degeneration. This clinically significant phenomenon warrants in-depth investigation into its underlying patho-mechanisms. Neurosurgeons should perform thorough preoperative evaluations with particular attention to diabetic neuropathy severity in cervical spondylosis patients. For individuals with HbA1c levels\u0026thinsp;\u0026ge;\u0026thinsp;8.0%, a period of pharmacological intervention targeting strict glycaemic control is strongly recommended prior to surgical intervention. Failure to address these metabolic parameters may predispose patients to postoperative motor dysfunction or de novo neurological deficits.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor Contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBGL conceptualized the ideas. PW drafted, and wrote the original manuscript. PW conducted the experiments. BWX collected all the data. BXW, DZ, THR, and BGL revised the manuscript. All the authors have reviewed the manuscript and approved its submission.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was funded by the National Natural Science Foundation of China (No. 82272524) and the High Level Public Health Technology Talent Construction Project (NO. Leading Talent-02\u0026ndash;05).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data that support the findings of this study are available from the corresponding author, Professor Baoge Liu, upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics Approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis Clinical retrospective study was conducted according to the guidelines of the Declaration of Helsinki and approved by the Ethical Committee of Beijing Tiantan Hospital, Capital Medical University（KY2022-248-02） with a waiver of written informed consent. All animal experiments were conducted in accordance with the Guidelines for Institutional Animal Care and Use Committee (2024363). The procedures were approved by the Ethics Committee of Beijing Neurosurgical Institute. We reconfirmed our manuscript that the study had adhered to the ARRIVE guidelines.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDisclosure statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo potential conflict of interest was reported by the author(s).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor details\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e1\u003c/sup\u003eDepartment of Orthopaedic Surgery, Beijing Tiantan Hospital, Capital Medical University, No. 119 South 4th Ring West Road, Fengtai District, Beijing, 100070, China.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eTetreault L, Ibrahim A, C\u0026ocirc;t\u0026eacute; P, Singh A, Fehlings MG (2016) A systematic review of clinical and surgical predictors of complications following surgery for degenerative cervical myelopathy. 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Neurosurgery 89(6):E308\u0026ndash;E309\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePark CH, Min KB, Min JY, Kim DH, Seo KM, Kim DK (2021) Strong association of type 2 diabetes with degenerative lumbar spine disorders. Sci Rep 11(1):16472\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKrolak T, Chan KY, Kaplan L, Huang Q, Wu J, Zheng Q et al (2022) A High-Efficiency AAV for Endothelial Cell Transduction Throughout the Central Nervous System. Nat Cardiovasc Res 1(4):389\u0026ndash;400\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSingh A, Krisa L, Frederick KL, Sandrow-Feinberg H, Balasubramanian S, Stackhouse SK et al (2014) Forelimb locomotor rating scale for behavioral assessment of recovery after unilateral cervical spinal cord injury in rats. J Neurosci Methods 226:124\u0026ndash;131\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"diabetes mellitus, cervical spine surgery, motor nerve function, neuronal cells, axonal degeneration, rat animal experiment","lastPublishedDoi":"10.21203/rs.3.rs-7264091/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7264091/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground \u003c/strong\u003eTo analyse the effect of diabetes on motor nerve function recovery in patients who underwent cervical decompression surgery and to explore the possible mechanisms of this effect through animal experiments.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e The medical records and follow-up data for patients with cervical spondylosis who underwent cervical spine surgery from January 2021 to December 2023 were retrospectively analysed. The patients were divided into diabetes mellitus (DM) and non-DM groups. The clinical characteristics, preoperative and postoperative Japanese Orthopaedic Association (JOA) scores, JOA recovery rates (JOA-RR), neck disability index (NDI) values, and visual analogue scale (VAS) scores for the two groups were compared, and factors independently associated with motor nerve function recovery were identified via multivariable linear regression analysis. The findings of these analyses were validated in animal experiments involving adult male Sprague‒Dawley (SD) rats with type 2 DM and the same number of healthy SD rats as the control group. Both groups of rats underwent surgery to model incomplete cervical spinal cord injury. The forelimb locomotor assessment scale (FLAS) was used to evaluate the forelimb movement of the rats in the two groups on the 1\u003csup\u003est\u003c/sup\u003e, 7\u003csup\u003eth\u003c/sup\u003e, 14\u003csup\u003eth\u003c/sup\u003e, and 30\u003csup\u003eth\u003c/sup\u003e days after surgery, and motor-evoked potentials (MEPs) were measured. The numbers of neurons and functional changes in the axons and other organelles of the samples at the site of injury to the cervical spinal cord were determined via electron microscopy and light microscopy on the day of and 30 days after the operation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e A total of 129 patients who underwent cervical spine surgery were analysed in this study, including 59 in the DM group and 70 in the non-DM group. The median age, mean preoperative glycosylated haemoglobin (HbA1c) level, mean preoperative glucose level, and mean volume of intraoperative bleeding in the DM group were greater than those in the non-DM group, whereas the JOA, JOA-RR, NDI, VAS neck (VAS (N)), and VAS limbs (VAS (L)) scores within six months after surgery were greater for the non-DM group than for the DM group. Multivariate linear regression suggested that age and the preoperative HbA1c level were independently associated with the postoperative JOA score, the preoperative blood glucose level was independently associated with the postoperative NDI, and the surgical segment and preoperative blood glucose level were independent risk factors for the postoperative VAS (L) score. The animal experiments revealed that both groups of rats began to recover motor nerve function within 7 days after incomplete cervical spinal cord injury; the FLAS score of the non-DM group on the 7\u003csup\u003eth\u003c/sup\u003e and 14\u003csup\u003eth\u003c/sup\u003e days was greater than that of the DM group, whereas the FLAS score on the 30\u003csup\u003eth\u003c/sup\u003e day was not significantly different between the two groups. Compared with those of individuals in the non-DM group, the latency and amplitude of upper-extremity MEPs were both lower for individuals in the DM group. The latencies of the lower-extremity MEPs were similar, but their amplitudes were lower for the DM group than for the non-DM group. Under light microscopy, the individuals in the DM group presented more severe spinal cord tissue necrosis, a more severely scattered central canal, and fewer neurons in the affected area than did the individuals in the non-DM group. Under high-resolution electron microscopy, in the DM group, the axons exhibited lamellar separation and tissue swelling, and the tissue structure was incomplete on the 30\u003csup\u003eth\u003c/sup\u003e day after surgery.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e The poor recovery of motor nerve function observed in DM patients following cervical decompression may be related to neuronal necrosis and loss and axonal degeneration caused by the high-glucose environment in these individuals.\u003c/p\u003e","manuscriptTitle":"The effects of diabetes on the recovery of motor nerve function after cervical decompression surgery and associated mechanisms","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-21 12:08:17","doi":"10.21203/rs.3.rs-7264091/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"19ebb18d-a358-4190-b259-7d1c4a9c060a","owner":[],"postedDate":"August 21st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-10-06T20:38:21+00:00","versionOfRecord":[],"versionCreatedAt":"2025-08-21 12:08:17","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7264091","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7264091","identity":"rs-7264091","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}