Association of Total Small Bowel Length with Glycaemic Control and Metabolic Syndrome in Metabolic and Bariatric Surgery Patients: A Cross-Sectional Study in a Taiwanese Cohort

Association of Total Small Bowel Length with Glycaemic Control and Metabolic Syndrome in Metabolic and Bariatric Surgery Patients: A Cross-Sectional Study in a Taiwanese Cohort | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Association of Total Small Bowel Length with Glycaemic Control and Metabolic Syndrome in Metabolic and Bariatric Surgery Patients: A Cross-Sectional Study in a Taiwanese Cohort Choon Woon NGO, Nilay RAI, Mohd Kamarulariffin KAMARUDIN, Matt HSIN, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7387810/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 22 Mar, 2026 Read the published version in Obesity Surgery → Version 1 posted 11 You are reading this latest preprint version Abstract The small intestine plays a vital role in nutrient absorption, hormone regulation, and glucose metabolism, and its anatomical variability may contribute to differences in metabolic outcomes. While the length of the total small bowel (TSBL) has been recognized to vary significantly between individuals, its potential metabolic implications, especially in the context of glycaemic control and metabolic syndrome, remain under-investigated. In the setting of metabolic and bariatric surgery (MBS), where metabolic improvements are often dramatic, understanding the anatomical contributions to these outcomes could enhance patient stratification and procedural planning. Prior studies have suggested associations between small bowel length and body height, but limited research has examined its relationship with biochemical parameters such as glycated haemoglobin (HbA1c) and the broader constellation of metabolic syndrome features. This study aimed to assess the relationship between TSBL and key glycaemic parameters, particularly HbA1c levels, as well as the presence of metabolic syndrome, in patients undergoing primary bariatric bypass surgery. We conducted a comprehensive cross-sectional analysis in a high-volume bariatric center in Taiwan, applying standardized bowel length measurements and rigorous exclusion criteria to minimize confounding factors such as medication use and renal dysfunction. Through a combination of univariate and multivariate regression analyses, the study sought to determine whether anatomical length variations of the small bowel could be linked to measurable differences in metabolic profiles, independent of traditional anthropometric indicators like body mass index (BMI). Total Small Bowel Length Glycaemic Control Metabolic Syndrome HbA1c Figures Figure 1 Figure 2 INTRODUCTION Type 2 diabetes mellitus (T2DM) remained one of the leading global health challenges, characterized by impaired glucose regulation and associated with significant morbidity and mortality. Metabolic and bariatric surgery (MBS) had emerged as an effective treatment for obesity and T2DM, with mounting evidences supporting its role in inducing remission of diabetes mellitus and improving insulin sensitivity, independent of weight loss. ( 1 ) However, the precise mechanisms underlying the metabolic benefits of MBS procedures were not yet fully elucidated. Anatomical variations, particularly those of the gastrointestinal tract, might offer insights into the heterogeneity of metabolic outcomes following surgery. Among these, total small bowel length (TSBL) had attracted growing interest. The small intestine is central to nutrient absorption and plays a critical role in regulating postprandial glucose and hormonal responses. Previous studies had established that small bowel length varied significantly between individuals, with measurements in live patients ranging from 380 to over 1000 cm. ( 2 – 4 ) Earlier research had demonstrated positive correlations between small bowel length and body height, as well as weak but notable associations with glycaemic markers such as glycated haemoglobin (HbA1c). ( 2 , 5 ) In their Taiwanese cohort, Almalki et al. reported that height and HbA1C levels independently predicted small bowel length among patients undergoing sleeve gastrectomy. ( 2 ) Similar trends had been observed in Indian and Middle Eastern populations, suggesting a possible ethnic and dietary influence on intestinal morphology. ( 3 , 5 ) According to a research, there was suggestion that T2DM and length of common channel had significant relation in terms of control of the disease after laparoscopic Roux-en-Y gastric bypass. Short common channel which was one third of total alimentary limb length (TALL) of less than 100cm could achieved control in 93% patients; whereas a longer common channel that’s more than two third of TALL achieved control in 58% patients. ( 6 ) On the other hand, BMI did not find any correlations with total small bowel length as it is a ratio of weight and height, therefore both the parameters could ended up having direct relationship with TSBL. BMI, being a ratio would only become insignificant in that aspect. ( 5 ) The role of the gastrointestinal tract in glucose metabolism had been reinforced by studies on incretin hormones, particularly glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), which were secreted in response to nutrient delivery to the distal ileum. Rubino and Marescaux (2004) demonstrated that duodenojejunal exclusion in animal models improved glycaemic profiles, independent of weight loss. ( 7 ) This finding had been supported by clinical observations that intestinal bypass procedures at further downstream location at distal ileum resulted in greater metabolic improvements, likely due to early and enhanced GLP-1 stimulation. ( 8 , 9 ) Despite these, there remained a paucity of clinical studies directly examining the relationship between measured small bowel length and glycaemic parameters in patients undergoing bypass surgery. Most previous works had focused on sleeve gastrectomy, a restrictive procedure with limited bypass of the small intestine. ( 10 – 13 ) The current study sought to address this gap by analyzing a large, medication-naïve Taiwanese cohort undergoing bypass procedures with intraoperatively measured total small bowel length (TSBL). By excluding patients on glucose-lowering medications and accounting for renal function, this study offered a clearer perspective on the intrinsic relationship between total small bowel length and metabolic parameters. We hypothesized that longer small bowel length would be associated with higher HbA1c levels and increased risk of metabolic syndrome, independent of body mass index (BMI). This investigation might have implications for individualized surgical planning and enhancing our understanding of the role of gastrointestinal system in blood glucose regulations. METHODOLOGY Study Design and Study Population This cross-sectional study was conducted at our center. The study included all patients who underwent primary bowel bypass procedures, namely proximal jejunal bypass (PJB) and duodenojejunal bypass (DJB), between January 1, 2022, and December 31, 2023. Approval to conduct this study was granted by the institution’s ethics committee and scientific advisory board. By utilizing PS Power and Sample Size Calculations, with a target power of 80% and a significance level of 0.05, we estimate that the total sample size required was 430. A total of 801 patient records were screened. After applying exclusion criteria, 478 patients were included in the final analysis. Excluded patients included those who underwent revisional procedures (n = 22), used diabetic medications including oral hypoglycaemic agents and insulin (n = 163), used GLP-1 analogues within 3 months prior to surgery (n = 17), or had impaired renal function (eGFR ≤ 80 mL/min/1.73 m²; n = 121). Written informed consent was obtained from all patients who participated in this cross-sectional study. Demographic and Clinical Data The data were extracted from the hospital’s electronic medical record which was securely stored to ensure confidentiality. The demographic data collected included information such as age, sex, height, initial weight, and the highest recorded weight. Information on comorbidities, particularly the presence of hypertension, diabetes mellitus, and obstructive sleep apnoea, were gathered too. The data of the initial blood investigations included full blood count, renal profile, liver profile, diabetes mellitus profile, lipid profile, thyroid function test, and cortisol level. Surgical Technique The bowel bypass procedure had been the most common surgery performed at the our center since 2020. The two main types of surgeries conducted were PJB and DJB. All surgical procedures were performed using a standardized operative techniques by two experienced bariatric surgeons, each with more than 10 and 20 years of experience respectively. During the surgery, total small bowel length (TSBL) was measured before resecting the bowel. The measurement was standardized from the ligament of Treitz to the terminal ileum, using a bowel grasper marked at 5 and 10 cm intervals. The total alimentary limb length (TALL) is subsequently tailored to fall within the range of 300 to 350cm, prior to bowel resection and bypass anastomosis. Outcome Measures Outcome Measures The primary outcome was the association between TSBL and HbA1c levels. Secondary outcomes included correlations between TSBL and height, sex, and the presence of metabolic syndrome. Metabolic syndrome was diagnosed using Taiwanese national criteria, which required the presence of at least three of the followings: abdominal obesity (waist circumference ≥ 90 cm in males, ≥ 80 cm in females), blood pressure ≥ 130/85 mmHg, fasting glucose ≥ 100 mg/dL, serum triglyceride ≥ 150 mg/dL, and HDL cholesterol ≤ 40 mg/dL in males or ≤ 50 mg/dL in females. Statistical Analysis Data were analysed using SPSS version 25. Continuous variables were assessed for normality and expressed as mean ± standard deviation or median with interquartile ranges. Bivariate relationships were assessed using linear regression, and multivariate linear regression models were used to determine independent predictors of TSBL. A significance level of p < 0.05 was considered statistically significant. Post hoc power analysis indicated sufficient power to detect medium effect sizes with the given sample size (n = 478). RESULTS Patient Characteristics Out of 801 patient records reviewed, 478 patients fulfilled all inclusion criteria and were included in the final analysis. The cohort consisted of 215 male (45%) and 263 female (55%) patients. The mean age was 39.1 ± 11.5 years. Median total small bowel length (TSBL) was longer in males (690 cm) than in females (630 cm). The distribution of TSBL varied widely, ranging from 480 to 950 cm. Notably, a higher proportion of patients with longer TSBL exhibited metabolic syndrome characteristics. Associations Between TSBL and Clinical Parameters Multivariate linear regression revealed the following significant findings: HbA1c: For every 1% increase in HbA1c, there was a corresponding increase of 10.81 cm in TSBL (p = 0.0483). This suggests a linear relationship between poor glycaemic control and increased small bowel length. Height: A 1cm increase in body height was associated with an increase of 1.8 cm in TSBL (p = 0.0156), reaffirming height as a key anatomical predictor. Sex: Male patients had, on average, 33.7 cm longer small intestines compared to females (p = 0.0066). Metabolic Syndrome: Presence of metabolic syndrome was associated with an 18.4 cm increase in TSBL (p = 0.0353), indicating a link between longer bowel anatomy and cardiometabolic risk factors. Body Mass Index: Height and weight have relation to increase the TSBL. However BMI does not have a direct relation to causing an increase in TSBL Predictive Model Summary The final multivariate model incorporating height, sex, HbA1c, and metabolic syndrome status explained 13.1% of the variance in TSBL (R² = 0.131). Although modest, the statistical model underscores independent relationships between physiological characteristics and small bowel length. Post Hoc Analysis and Visual Correlations Post hoc power analysis verified that the study was adequately powered (> 90%) to detect medium effect sizes (f² = 0.14) with the existing sample size. Height vs TSBL: Scatter plots confirmed a steady linear trend across increasing height. HbA1c vs TSBL: Patients were grouped in HbA1c brackets, revealing incremental increases in TSBL corresponding to each higher glycaemic group. Sex Differences: Bar graphs illustrated that male patients consistently exhibited greater TSBL than their female counterparts. Metabolic Syndrome Status: Boxplots demonstrated longer median TSBL among patients diagnosed with metabolic syndrome. Taken together, these findings substantiated consistent pattern: patients with longer small bowel lengths appeared to exhibit higher glycaemic levels and greater prevalence of metabolic syndrome. These results were particularly notable given that they were observed in a medication-naïve population, emphasizing the potential intrinsic influence of anatomical variation on metabolic health. The identified associations invited further exploration into how small bowel length might impact incretin hormone dynamics, nutrient absorption efficiency, and energy homeostasis—key pathways in understanding obesity-related insulin resistance. Figure 1 illustrated mean total small bowel length (TSBL) across key patient groups, demonstrating a clear trend of longer TSBL in males and in individuals with metabolic syndrome. Figure 2 illustrated that both male and female patients with metabolic syndrome exhibited longer mean TSBL than their counterparts without metabolic syndrome. The anatomical difference was more pronounced in males, supporting the observed associations in regression analysis. DISCUSSIONS The present study provided compelling evidence that anatomical variation in small bowel length was significantly associated with glycaemic control and metabolic issues. Specifically, individuals with longer total small bowel length (TSBL) were found to have higher HbA1c levels and a greater likelihood of meeting criteria for metabolic syndrome. These associations were observed independently of body mass index (BMI), highlighting that TSBL may serve as a previously under-appreciated determinant of metabolic function. One of the most notable findings was the positive correlation between HbA1c and TSBL. This relationship supports existing hypotheses that increased absorptive surface area and prolonged nutrient transit time in longer intestines may result in delayed but sustained glucose absorption, which in turn affects glycaemic regulation. Furthermore, extended TSBL could potentially reduce the rate and magnitude of distal gut hormone responses, such as GLP-1 and PYY, contributing to impaired satiety and insulin sensitivity. These mechanisms had been proposed in both animal models and clinical observations, ( 1 , 4 ) particularly in studies of bariatric surgery that manipulate intestinal anatomy. Additionally, the association of TSBL with metabolic syndrome added clinical relevance. Metabolic syndrome was a cluster of conditions linked to insulin resistance and elevated cardiovascular risk. The observed increase in TSBL among patients with metabolic syndrome may reflect an adaptive or maladaptive response in intestinal development. It could be either genetically or environmentally determined. The data also reaffirmed previous literatures demonstrating that male sex and greater height are predictors of longer TSBL, ( 2 , 8 ) although their interaction with metabolic outcomes remained elusive. The modest explanatory power of the predictive model (R² = 0.131) suggested that while TSBL was a significant factor, it was not the sole contributor to metabolic phenotype. Additional influences such as gut microbiota, diet, intestinal permeability, and endocrine function likely interacted with anatomical features to shape metabolic outcomes. Limitations of the study included its retrospective design, which precluded causal inference, and single-centered setting, which might limit generalizability. Intraoperative measurement of TSBL, though standardized and consistent between surgeons, may still be subject to variability due to techniques or bowel tension. Furthermore, we did not assess hormonal profiles or perform functional analyses of nutrient absorption, which would be necessary to establish pathophysiological links. CONCLUSION The results suggested that small bowel length was associated with glycaemic control and metabolic risk, independent of BMI. These findings highlighted the potential role of intestinal morphology in metabolic regulation. Specifically, the observation that individuals with higher HbA1c levels tend to have longer TSBL raised important questions about the interplay between intestinal absorptive surface area and glucose metabolism. While BMI had been used as a surrogate marker of metabolic status, our findings suggested that internal anatomical variations such as TSBL could provide additional insight into metabolic dysregulation mechanisms. This association, observed in a medication-naïve population, indicated that the small bowel might contributed more actively to metabolic disturbances than previously recognized. Further prospective studies were warranted to explore the physiological pathways linking bowel length to glycaemic profiles, including the role of incretin hormones, nutrient transit time, and mucosal adaptation. Understanding these mechanisms might help to guide personalized approaches to metabolic bariatric surgery and potentially opened new frontiers for non-surgical interventions targeting intestinal function. This study demonstrated longer small bowel length was associated with higher HbA1c levels and increased risk of metabolic syndrome, even in the absence of diabetic medication use. These findings supported the notion that anatomical factors such as TSBL might influence metabolic physiology and suggested that small bowel length could be considered in preoperative risk assessment and tailored surgical planning. Future research should include prospective, multi-center trials that evaluate changes in hormonal responses and metabolic parameters in relation to measured small bowel length. Investigating how TSBL interacts with dietary intake, microbiota composition, and other modifiable factors may yield insights for both surgical and non-surgical interventions in the management of metabolic diseases. Declarations Author Contribution C.W.N., M.H. and C.K.H. conceived of the presented idea. C.W.N. and C.K.H developed the theory. C.W.N. collected the data from the medical records. M.K.K and N.R. performed the computations and verified the analytical methods. C.K.H. encouraged C.W.N. to investigate multivariate findings and results, whilst supervised the findings of this work. All authors discussed the results and contributed to the final manuscript.C.W.N. = Choon Woon NGON.R. = Nilay RAIM.K.K. = Mohd Kamarularifin KAMARUDINM.H. = Matt HSINC.K.H. = Chih-Kun HUANG Acknowledgement We would like to acknowledge Dr. Wei Ching OOI from Ipoh Hospital, Malaysia for compiling and drafting of the paper. References Murray S, Tulloch A, Gold MS, Avena NM. Hormonal and neural mechanisms of food reward, eating behaviour and obesity. Nat Rev Endocrinol. 2014;10(9):540–52. Almalki OM, Soong TC, Lee WJ, Chen JC, Wu CC, Lee YC. Variation in Small Bowel Length and Its Influence on the Outcomes of Sleeve Gastrectomy. Obes Surg. 2021;31(1):36–42. Bekheit M, Ibrahim MY, Tobar W, Galal I, Elward AS. Correlation Between the Total Small Bowel Length and Anthropometric Measures in Living Humans: Cross-Sectional Study. Obes Surg. 2020;30(2):681–6. Ignacio J. Guzman, Laurie L. Fitch, Varco RL, Buchwald H. Small Bowel Length in Hyperlipidaemia and Massive Obesity. American Journal of Clinical Nutrition. 1977;30(7):1006–8. Purandare A, Phalgune D, Shah S. Variability of Length of Small Intestine in Indian Population and Its Correlation with Type 2 Diabetes Mellitus and Obesity. Obes Surg. 2019;29(10):3149–53. Käkelä P, Rantanen T, Virtanen KA. The Importance of Intestinal Length in Triglyceride Metabolism and in Predicting the Outcomes of Comorbidities in Laparoscopic Roux-en-Y Gastric Bypass—a Narrative Review. Obesity Surgery. 2021;31(7):3291–5. Rubino F, Marescaux J. Effect of duodenal-jejunal exclusion in a non-obese animal model of type 2 diabetes: a new perspective for an old disease. Ann Surg. 2004;239(1):1–11. Lee WJ, Aung L. Metabolic Surgery for Type 2 Diabetes Mellitus: Experience from Asia. Diabetes Metab J. 2016;40(6):433–43. Thaler JP, Cummings DE. Minireview: Hormonal and metabolic mechanisms of diabetes remission after gastrointestinal surgery. Endocrinology. 2009;150(6):2518–25. Chen JC, Shen CY, Lee WJ, Tsai PL, Lee YC. Protein deficiency after gastric bypass: The role of common limb length in revision surgery. Surg Obes Relat Dis. 2019;15(3):441–6. Kaska L, Sledzinski T, Chomiczewska A, Dettlaff-Pokora A, Swierczynski J. Improved glucose metabolism following bariatric surgery is associated with increased circulating bile acid concentrations and remodeling of the gut microbiome. World J Gastroenterol. 2016;22(39):8698–719. Slagter N, de Heide LJM, Jutte EH, Kaijser MA, Damen SL, van Beek AP, et al. Tailoring limb length based on total small bowel length in one anastomosis gastric bypass surgery (TAILOR study): study protocol for a randomized controlled trial. Trials. 2022;23(1):526. Mika A, Kaska L, Proczko-Stepaniak M, Chomiczewska A, Swierczynski J, Smolenski RT, et al. Evidence That the Length of Bile Loop Determines Serum Bile Acid Concentration and Glycemic Control After Bariatric Surgery. Obes Surg. 2018;28(11):3405–14. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 22 Mar, 2026 Read the published version in Obesity Surgery → Version 1 posted Editorial decision: Revision requested 21 Oct, 2025 Reviews received at journal 17 Oct, 2025 Reviewers agreed at journal 07 Oct, 2025 Reviewers agreed at journal 07 Oct, 2025 Reviewers agreed at journal 06 Oct, 2025 Reviews received at journal 03 Sep, 2025 Reviewers agreed at journal 29 Aug, 2025 Reviewers invited by journal 29 Aug, 2025 Editor assigned by journal 28 Aug, 2025 Submission checks completed at journal 26 Aug, 2025 First submitted to journal 16 Aug, 2025 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-7387810","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":510298051,"identity":"bfd88e7f-ca45-48b7-a9c8-ec8e4c66dce2","order_by":0,"name":"Choon Woon NGO","email":"","orcid":"","institution":"Enche' Besar Hajjah Khalsom Kluang Hospital","correspondingAuthor":false,"prefix":"","firstName":"Choon","middleName":"Woon","lastName":"NGO","suffix":""},{"id":510298053,"identity":"479f74d3-2dc0-40b8-ba99-f4b5110560be","order_by":1,"name":"Nilay RAI","email":"","orcid":"","institution":"James Paget University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Nilay","middleName":"","lastName":"RAI","suffix":""},{"id":510298055,"identity":"ffc9096e-84cc-4431-adb4-d40d213952e1","order_by":2,"name":"Mohd Kamarulariffin KAMARUDIN","email":"","orcid":"","institution":"National Institute of Health, Ministry of Health Malaysia","correspondingAuthor":false,"prefix":"","firstName":"Mohd","middleName":"Kamarulariffin","lastName":"KAMARUDIN","suffix":""},{"id":510298057,"identity":"ba64f59c-eb9c-4664-88cc-0333aa5d6759","order_by":3,"name":"Matt HSIN","email":"","orcid":"","institution":"China Medical University","correspondingAuthor":false,"prefix":"","firstName":"Matt","middleName":"","lastName":"HSIN","suffix":""},{"id":510298058,"identity":"d6b3ff9a-9f54-4a73-afa0-5b1e2f3df7fb","order_by":4,"name":"Chih-Kun HUANG","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6klEQVRIiWNgGAWjYDCCAwwMjI0NIBbzMbAAGzvxWtjSGBgSgBQz8Vp4zMBaGAhp4bt9gPHjzB2H5c3513x78PHHNnk+ZgbGDx9zcGuRPJfALLnxzGHDnTPebjeckXDbsI2ZgVly5jbcWgzOMLAxPmw7zLjhxtlt0jwJtxmBWtiYeYnQYr/hxplnIC32xGnZ2HY4ccP5HjaQlkSCWiTPMDZLzmxLT95wg81Mckba7eQ2ZpAIHi18Z5gPfuxts7bdcP7wM4kPNrdt57c3H/zwEY8WYKw0QGiJBHQRgoD/AJEKR8EoGAWjYMQBAM2lVTH/S6cvAAAAAElFTkSuQmCC","orcid":"","institution":"China Medical University","correspondingAuthor":true,"prefix":"","firstName":"Chih-Kun","middleName":"","lastName":"HUANG","suffix":""}],"badges":[],"createdAt":"2025-08-16 13:38:38","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7387810/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7387810/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s11695-026-08594-5","type":"published","date":"2026-03-22T15:58:22+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":90880941,"identity":"4eedf86f-f4e1-4762-9411-71309a112dbd","added_by":"auto","created_at":"2025-09-09 09:39:20","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":144356,"visible":true,"origin":"","legend":"\u003cp\u003eMean Total Small Bowel Length (TSBL) across Sex\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7387810/v1/0ea292f3b6aad32ae14a1dc7.png"},{"id":90880986,"identity":"020f0440-e15f-4d9d-b515-a3f909acaef7","added_by":"auto","created_at":"2025-09-09 09:39:27","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":171036,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of Mean Total Small Bowel Length (TSBL) by Sex and Metabolic Syndrome Status\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7387810/v1/75b465ae62fddf6f407df9b7.png"},{"id":105224746,"identity":"c3b0f65b-c8da-4fe2-8d68-c33e1e4ce22f","added_by":"auto","created_at":"2026-03-23 16:15:55","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":717478,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7387810/v1/114ad3c1-ed61-4b0b-b55c-8ed8fc3e8084.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Association of Total Small Bowel Length with Glycaemic Control and Metabolic Syndrome in Metabolic and Bariatric Surgery Patients: A Cross-Sectional Study in a Taiwanese Cohort","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eType 2 diabetes mellitus (T2DM) remained one of the leading global health challenges, characterized by impaired glucose regulation and associated with significant morbidity and mortality. Metabolic and bariatric surgery (MBS) had emerged as an effective treatment for obesity and T2DM, with mounting evidences supporting its role in inducing remission of diabetes mellitus and improving insulin sensitivity, independent of weight loss. (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e) However, the precise mechanisms underlying the metabolic benefits of MBS procedures were not yet fully elucidated.\u003c/p\u003e\u003cp\u003eAnatomical variations, particularly those of the gastrointestinal tract, might offer insights into the heterogeneity of metabolic outcomes following surgery. Among these, total small bowel length (TSBL) had attracted growing interest. The small intestine is central to nutrient absorption and plays a critical role in regulating postprandial glucose and hormonal responses. Previous studies had established that small bowel length varied significantly between individuals, with measurements in live patients ranging from 380 to over 1000 cm. (\u003cspan additionalcitationids=\"CR3\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e)\u003c/p\u003e\u003cp\u003eEarlier research had demonstrated positive correlations between small bowel length and body height, as well as weak but notable associations with glycaemic markers such as glycated haemoglobin (HbA1c). (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e) In their Taiwanese cohort, Almalki et al. reported that height and HbA1C levels independently predicted small bowel length among patients undergoing sleeve gastrectomy. (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e) Similar trends had been observed in Indian and Middle Eastern populations, suggesting a possible ethnic and dietary influence on intestinal morphology. (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e)\u003c/p\u003e\u003cp\u003eAccording to a research, there was suggestion that T2DM and length of common channel had significant relation in terms of control of the disease after laparoscopic Roux-en-Y gastric bypass. Short common channel which was one third of total alimentary limb length (TALL) of less than 100cm could achieved control in 93% patients; whereas a longer common channel that\u0026rsquo;s more than two third of TALL achieved control in 58% patients. (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e)\u003c/p\u003e\u003cp\u003eOn the other hand, BMI did not find any correlations with total small bowel length as it is a ratio of weight and height, therefore both the parameters could ended up having direct relationship with TSBL. BMI, being a ratio would only become insignificant in that aspect. (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e)\u003c/p\u003e\u003cp\u003eThe role of the gastrointestinal tract in glucose metabolism had been reinforced by studies on incretin hormones, particularly glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), which were secreted in response to nutrient delivery to the distal ileum. Rubino and Marescaux (2004) demonstrated that duodenojejunal exclusion in animal models improved glycaemic profiles, independent of weight loss. (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e) This finding had been supported by clinical observations that intestinal bypass procedures at further downstream location at distal ileum resulted in greater metabolic improvements, likely due to early and enhanced GLP-1 stimulation. (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e)\u003c/p\u003e\u003cp\u003eDespite these, there remained a paucity of clinical studies directly examining the relationship between measured small bowel length and glycaemic parameters in patients undergoing bypass surgery. Most previous works had focused on sleeve gastrectomy, a restrictive procedure with limited bypass of the small intestine. (\u003cspan additionalcitationids=\"CR11 CR12\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e) The current study sought to address this gap by analyzing a large, medication-na\u0026iuml;ve Taiwanese cohort undergoing bypass procedures with intraoperatively measured total small bowel length (TSBL). By excluding patients on glucose-lowering medications and accounting for renal function, this study offered a clearer perspective on the intrinsic relationship between total small bowel length and metabolic parameters.\u003c/p\u003e\u003cp\u003eWe hypothesized that longer small bowel length would be associated with higher HbA1c levels and increased risk of metabolic syndrome, independent of body mass index (BMI). This investigation might have implications for individualized surgical planning and enhancing our understanding of the role of gastrointestinal system in blood glucose regulations.\u003c/p\u003e"},{"header":"METHODOLOGY","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStudy Design and Study Population\u003c/h2\u003e\u003cp\u003eThis cross-sectional study was conducted at our center. The study included all patients who underwent primary bowel bypass procedures, namely proximal jejunal bypass (PJB) and duodenojejunal bypass (DJB), between January 1, 2022, and December 31, 2023. Approval to conduct this study was granted by the institution\u0026rsquo;s ethics committee and scientific advisory board. By utilizing PS Power and Sample Size Calculations, with a target power of 80% and a significance level of 0.05, we estimate that the total sample size required was 430. A total of 801 patient records were screened. After applying exclusion criteria, 478 patients were included in the final analysis. Excluded patients included those who underwent revisional procedures (n\u0026thinsp;=\u0026thinsp;22), used diabetic medications including oral hypoglycaemic agents and insulin (n\u0026thinsp;=\u0026thinsp;163), used GLP-1 analogues within 3 months prior to surgery (n\u0026thinsp;=\u0026thinsp;17), or had impaired renal function (eGFR\u0026thinsp;\u0026le;\u0026thinsp;80 mL/min/1.73 m\u0026sup2;; n\u0026thinsp;=\u0026thinsp;121). Written informed consent was obtained from all patients who participated in this cross-sectional study.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eDemographic and Clinical Data\u003c/h3\u003e\n\u003cp\u003eThe data were extracted from the hospital\u0026rsquo;s electronic medical record which was securely stored to ensure confidentiality. The demographic data collected included information such as age, sex, height, initial weight, and the highest recorded weight. Information on comorbidities, particularly the presence of hypertension, diabetes mellitus, and obstructive sleep apnoea, were gathered too. The data of the initial blood investigations included full blood count, renal profile, liver profile, diabetes mellitus profile, lipid profile, thyroid function test, and cortisol level.\u003c/p\u003e\n\u003ch3\u003eSurgical Technique\u003c/h3\u003e\n\u003cp\u003eThe bowel bypass procedure had been the most common surgery performed at the our center since 2020. The two main types of surgeries conducted were PJB and DJB. All surgical procedures were performed using a standardized operative techniques by two experienced bariatric surgeons, each with more than 10 and 20 years of experience respectively. During the surgery, total small bowel length (TSBL) was measured before resecting the bowel. The measurement was standardized from the ligament of Treitz to the terminal ileum, using a bowel grasper marked at 5 and 10 cm intervals. The total alimentary limb length (TALL) is subsequently tailored to fall within the range of 300 to 350cm, prior to bowel resection and bypass anastomosis.\u003c/p\u003e\n\u003ch3\u003eOutcome Measures\u003c/h3\u003e\n\u003cdiv class=\"Heading\"\u003eOutcome Measures\u003c/div\u003e\u003cp\u003eThe primary outcome was the association between TSBL and HbA1c levels. Secondary outcomes included correlations between TSBL and height, sex, and the presence of metabolic syndrome. Metabolic syndrome was diagnosed using Taiwanese national criteria, which required the presence of at least three of the followings: abdominal obesity (waist circumference\u0026thinsp;\u0026ge;\u0026thinsp;90 cm in males, \u0026ge;\u0026thinsp;80 cm in females), blood pressure\u0026thinsp;\u0026ge;\u0026thinsp;130/85 mmHg, fasting glucose\u0026thinsp;\u0026ge;\u0026thinsp;100 mg/dL, serum triglyceride\u0026thinsp;\u0026ge;\u0026thinsp;150 mg/dL, and HDL cholesterol\u0026thinsp;\u0026le;\u0026thinsp;40 mg/dL in males or \u0026le;\u0026thinsp;50 mg/dL in females.\u003c/p\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003eStatistical Analysis\u003c/h2\u003e\u003cp\u003eData were analysed using SPSS version 25. Continuous variables were assessed for normality and expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation or median with interquartile ranges. Bivariate relationships were assessed using linear regression, and multivariate linear regression models were used to determine independent predictors of TSBL. A significance level of p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant. Post hoc power analysis indicated sufficient power to detect medium effect sizes with the given sample size (n\u0026thinsp;=\u0026thinsp;478).\u003c/p\u003e\u003c/div\u003e"},{"header":"RESULTS","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003ePatient Characteristics\u003c/h2\u003e\u003cp\u003eOut of 801 patient records reviewed, 478 patients fulfilled all inclusion criteria and were included in the final analysis. The cohort consisted of 215 male (45%) and 263 female (55%) patients. The mean age was 39.1\u0026thinsp;\u0026plusmn;\u0026thinsp;11.5 years. Median total small bowel length (TSBL) was longer in males (690 cm) than in females (630 cm). The distribution of TSBL varied widely, ranging from 480 to 950 cm. Notably, a higher proportion of patients with longer TSBL exhibited metabolic syndrome characteristics.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eAssociations Between TSBL and Clinical Parameters\u003c/h3\u003e\n\u003cp\u003eMultivariate linear regression revealed the following significant findings:\u003c/p\u003e\u003cp\u003e\u003col\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eHbA1c: For every 1% increase in HbA1c, there was a corresponding increase of 10.81 cm in TSBL (p\u0026thinsp;=\u0026thinsp;0.0483). This suggests a linear relationship between poor glycaemic control and increased small bowel length.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eHeight: A 1cm increase in body height was associated with an increase of 1.8 cm in TSBL (p\u0026thinsp;=\u0026thinsp;0.0156), reaffirming height as a key anatomical predictor.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eSex: Male patients had, on average, 33.7 cm longer small intestines compared to females (p\u0026thinsp;=\u0026thinsp;0.0066).\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eMetabolic Syndrome: Presence of metabolic syndrome was associated with an 18.4 cm increase in TSBL (p\u0026thinsp;=\u0026thinsp;0.0353), indicating a link between longer bowel anatomy and cardiometabolic risk factors.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eBody Mass Index: Height and weight have relation to increase the TSBL. However BMI does not have a direct relation to causing an increase in TSBL\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003c/ol\u003e\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003ePredictive Model Summary\u003c/h2\u003e\u003cp\u003eThe final multivariate model incorporating height, sex, HbA1c, and metabolic syndrome status explained 13.1% of the variance in TSBL (R\u0026sup2; = 0.131). Although modest, the statistical model underscores independent relationships between physiological characteristics and small bowel length.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003ePost Hoc Analysis and Visual Correlations\u003c/h2\u003e\u003cp\u003ePost hoc power analysis verified that the study was adequately powered (\u0026gt;\u0026thinsp;90%) to detect medium effect sizes (f\u0026sup2; = 0.14) with the existing sample size.\u003c/p\u003e\u003cp\u003e\u003col\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eHeight vs TSBL: Scatter plots confirmed a steady linear trend across increasing height.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eHbA1c vs TSBL: Patients were grouped in HbA1c brackets, revealing incremental increases in TSBL corresponding to each higher glycaemic group.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eSex Differences: Bar graphs illustrated that male patients consistently exhibited greater TSBL than their female counterparts.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eMetabolic Syndrome Status: Boxplots demonstrated longer median TSBL among patients diagnosed with metabolic syndrome.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003c/ol\u003e\u003c/p\u003e\u003cp\u003eTaken together, these findings substantiated consistent pattern: patients with longer small bowel lengths appeared to exhibit higher glycaemic levels and greater prevalence of metabolic syndrome. These results were particularly notable given that they were observed in a medication-na\u0026iuml;ve population, emphasizing the potential intrinsic influence of anatomical variation on metabolic health. The identified associations invited further exploration into how small bowel length might impact incretin hormone dynamics, nutrient absorption efficiency, and energy homeostasis\u0026mdash;key pathways in understanding obesity-related insulin resistance.\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e illustrated mean total small bowel length (TSBL) across key patient groups, demonstrating a clear trend of longer TSBL in males and in individuals with metabolic syndrome.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e illustrated that both male and female patients with metabolic syndrome exhibited longer mean TSBL than their counterparts without metabolic syndrome. The anatomical difference was more pronounced in males, supporting the observed associations in regression analysis.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"DISCUSSIONS","content":"\u003cp\u003eThe present study provided compelling evidence that anatomical variation in small bowel length was significantly associated with glycaemic control and metabolic issues. Specifically, individuals with longer total small bowel length (TSBL) were found to have higher HbA1c levels and a greater likelihood of meeting criteria for metabolic syndrome. These associations were observed independently of body mass index (BMI), highlighting that TSBL may serve as a previously under-appreciated determinant of metabolic function.\u003c/p\u003e\u003cp\u003eOne of the most notable findings was the positive correlation between HbA1c and TSBL. This relationship supports existing hypotheses that increased absorptive surface area and prolonged nutrient transit time in longer intestines may result in delayed but sustained glucose absorption, which in turn affects glycaemic regulation. Furthermore, extended TSBL could potentially reduce the rate and magnitude of distal gut hormone responses, such as GLP-1 and PYY, contributing to impaired satiety and insulin sensitivity. These mechanisms had been proposed in both animal models and clinical observations, (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e) particularly in studies of bariatric surgery that manipulate intestinal anatomy.\u003c/p\u003e\u003cp\u003eAdditionally, the association of TSBL with metabolic syndrome added clinical relevance. Metabolic syndrome was a cluster of conditions linked to insulin resistance and elevated cardiovascular risk. The observed increase in TSBL among patients with metabolic syndrome may reflect an adaptive or maladaptive response in intestinal development. It could be either genetically or environmentally determined. The data also reaffirmed previous literatures demonstrating that male sex and greater height are predictors of longer TSBL, (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e) although their interaction with metabolic outcomes remained elusive.\u003c/p\u003e\u003cp\u003eThe modest explanatory power of the predictive model (R\u0026sup2; = 0.131) suggested that while TSBL was a significant factor, it was not the sole contributor to metabolic phenotype. Additional influences such as gut microbiota, diet, intestinal permeability, and endocrine function likely interacted with anatomical features to shape metabolic outcomes.\u003c/p\u003e\u003cp\u003eLimitations of the study included its retrospective design, which precluded causal inference, and single-centered setting, which might limit generalizability. Intraoperative measurement of TSBL, though standardized and consistent between surgeons, may still be subject to variability due to techniques or bowel tension. Furthermore, we did not assess hormonal profiles or perform functional analyses of nutrient absorption, which would be necessary to establish pathophysiological links.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eThe results suggested that small bowel length was associated with glycaemic control and metabolic risk, independent of BMI. These findings highlighted the potential role of intestinal morphology in metabolic regulation. Specifically, the observation that individuals with higher HbA1c levels tend to have longer TSBL raised important questions about the interplay between intestinal absorptive surface area and glucose metabolism. While BMI had been used as a surrogate marker of metabolic status, our findings suggested that internal anatomical variations such as TSBL could provide additional insight into metabolic dysregulation mechanisms. This association, observed in a medication-na\u0026iuml;ve population, indicated that the small bowel might contributed more actively to metabolic disturbances than previously recognized. Further prospective studies were warranted to explore the physiological pathways linking bowel length to glycaemic profiles, including the role of incretin hormones, nutrient transit time, and mucosal adaptation. Understanding these mechanisms might help to guide personalized approaches to metabolic bariatric surgery and potentially opened new frontiers for non-surgical interventions targeting intestinal function.\u003c/p\u003e\u003cp\u003eThis study demonstrated longer small bowel length was associated with higher HbA1c levels and increased risk of metabolic syndrome, even in the absence of diabetic medication use. These findings supported the notion that anatomical factors such as TSBL might influence metabolic physiology and suggested that small bowel length could be considered in preoperative risk assessment and tailored surgical planning.\u003c/p\u003e\u003cp\u003eFuture research should include prospective, multi-center trials that evaluate changes in hormonal responses and metabolic parameters in relation to measured small bowel length. Investigating how TSBL interacts with dietary intake, microbiota composition, and other modifiable factors may yield insights for both surgical and non-surgical interventions in the management of metabolic diseases.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eC.W.N., M.H. and C.K.H. conceived of the presented idea. C.W.N. and C.K.H developed the theory. C.W.N. collected the data from the medical records. M.K.K and N.R. performed the computations and verified the analytical methods. C.K.H. encouraged C.W.N. to investigate multivariate findings and results, whilst supervised the findings of this work. All authors discussed the results and contributed to the final manuscript.C.W.N. = Choon Woon NGON.R. = Nilay RAIM.K.K. = Mohd Kamarularifin KAMARUDINM.H. = Matt HSINC.K.H. = Chih-Kun HUANG\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eWe would like to acknowledge Dr. Wei Ching OOI from Ipoh Hospital, Malaysia for compiling and drafting of the paper.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eMurray S, Tulloch A, Gold MS, Avena NM. Hormonal and neural mechanisms of food reward, eating behaviour and obesity. Nat Rev Endocrinol. 2014;10(9):540\u0026ndash;52.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAlmalki OM, Soong TC, Lee WJ, Chen JC, Wu CC, Lee YC. Variation in Small Bowel Length and Its Influence on the Outcomes of Sleeve Gastrectomy. Obes Surg. 2021;31(1):36\u0026ndash;42.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBekheit M, Ibrahim MY, Tobar W, Galal I, Elward AS. Correlation Between the Total Small Bowel Length and Anthropometric Measures in Living Humans: Cross-Sectional Study. Obes Surg. 2020;30(2):681\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eIgnacio J. Guzman, Laurie L. Fitch, Varco RL, Buchwald H. Small Bowel Length in Hyperlipidaemia and Massive Obesity. American Journal of Clinical Nutrition. 1977;30(7):1006\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePurandare A, Phalgune D, Shah S. Variability of Length of Small Intestine in Indian Population and Its Correlation with Type 2 Diabetes Mellitus and Obesity. Obes Surg. 2019;29(10):3149\u0026ndash;53.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eK\u0026auml;kel\u0026auml; P, Rantanen T, Virtanen KA. The Importance of Intestinal Length in Triglyceride Metabolism and in Predicting the Outcomes of Comorbidities in Laparoscopic Roux-en-Y Gastric Bypass\u0026mdash;a Narrative Review. Obesity Surgery. 2021;31(7):3291\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRubino F, Marescaux J. Effect of duodenal-jejunal exclusion in a non-obese animal model of type 2 diabetes: a new perspective for an old disease. Ann Surg. 2004;239(1):1\u0026ndash;11.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLee WJ, Aung L. Metabolic Surgery for Type 2 Diabetes Mellitus: Experience from Asia. Diabetes Metab J. 2016;40(6):433\u0026ndash;43.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eThaler JP, Cummings DE. Minireview: Hormonal and metabolic mechanisms of diabetes remission after gastrointestinal surgery. Endocrinology. 2009;150(6):2518\u0026ndash;25.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChen JC, Shen CY, Lee WJ, Tsai PL, Lee YC. Protein deficiency after gastric bypass: The role of common limb length in revision surgery. Surg Obes Relat Dis. 2019;15(3):441\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKaska L, Sledzinski T, Chomiczewska A, Dettlaff-Pokora A, Swierczynski J. Improved glucose metabolism following bariatric surgery is associated with increased circulating bile acid concentrations and remodeling of the gut microbiome. World J Gastroenterol. 2016;22(39):8698\u0026ndash;719.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSlagter N, de Heide LJM, Jutte EH, Kaijser MA, Damen SL, van Beek AP, et al. Tailoring limb length based on total small bowel length in one anastomosis gastric bypass surgery (TAILOR study): study protocol for a randomized controlled trial. Trials. 2022;23(1):526.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMika A, Kaska L, Proczko-Stepaniak M, Chomiczewska A, Swierczynski J, Smolenski RT, et al. Evidence That the Length of Bile Loop Determines Serum Bile Acid Concentration and Glycemic Control After Bariatric Surgery. Obes Surg. 2018;28(11):3405\u0026ndash;14.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"obesity-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"obsu","sideBox":"Learn more about [Obesity Surgery](https://link.springer.com/journal/11695)","snPcode":"11695","submissionUrl":"https://submission.springernature.com/new-submission/11695/3","title":"Obesity Surgery","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Total Small Bowel Length, Glycaemic Control, Metabolic Syndrome, HbA1c","lastPublishedDoi":"10.21203/rs.3.rs-7387810/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7387810/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"The small intestine plays a vital role in nutrient absorption, hormone regulation, and glucose metabolism, and its anatomical variability may contribute to differences in metabolic outcomes. While the length of the total small bowel (TSBL) has been recognized to vary significantly between individuals, its potential metabolic implications, especially in the context of glycaemic control and metabolic syndrome, remain under-investigated. In the setting of metabolic and bariatric surgery (MBS), where metabolic improvements are often dramatic, understanding the anatomical contributions to these outcomes could enhance patient stratification and procedural planning. Prior studies have suggested associations between small bowel length and body height, but limited research has examined its relationship with biochemical parameters such as glycated haemoglobin (HbA1c) and the broader constellation of metabolic syndrome features.\nThis study aimed to assess the relationship between TSBL and key glycaemic parameters, particularly HbA1c levels, as well as the presence of metabolic syndrome, in patients undergoing primary bariatric bypass surgery. We conducted a comprehensive cross-sectional analysis in a high-volume bariatric center in Taiwan, applying standardized bowel length measurements and rigorous exclusion criteria to minimize confounding factors such as medication use and renal dysfunction. Through a combination of univariate and multivariate regression analyses, the study sought to determine whether anatomical length variations of the small bowel could be linked to measurable differences in metabolic profiles, independent of traditional anthropometric indicators like body mass index (BMI).","manuscriptTitle":"Association of Total Small Bowel Length with Glycaemic Control and Metabolic Syndrome in Metabolic and Bariatric Surgery Patients: A Cross-Sectional Study in a Taiwanese Cohort","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-09 09:38:55","doi":"10.21203/rs.3.rs-7387810/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-10-21T18:53:46+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-17T22:58:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"54084617197114869324347956354011575287","date":"2025-10-07T21:07:54+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"147989850080878907575817084348325205122","date":"2025-10-07T05:10:16+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"90018152318422695501724967992140036402","date":"2025-10-06T19:03:12+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-03T22:09:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"28331746475089261990106719088880913304","date":"2025-08-29T21:10:40+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-08-29T13:45:31+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-29T00:00:55+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-08-26T06:26:37+00:00","index":"","fulltext":""},{"type":"submitted","content":"Obesity Surgery","date":"2025-08-16T13:32:38+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"obesity-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"obsu","sideBox":"Learn more about [Obesity Surgery](https://link.springer.com/journal/11695)","snPcode":"11695","submissionUrl":"https://submission.springernature.com/new-submission/11695/3","title":"Obesity Surgery","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"6cbf159e-75c1-4c4e-8ee3-2fa26b991bba","owner":[],"postedDate":"September 9th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-03-23T16:13:09+00:00","versionOfRecord":{"articleIdentity":"rs-7387810","link":"https://doi.org/10.1007/s11695-026-08594-5","journal":{"identity":"obesity-surgery","isVorOnly":false,"title":"Obesity Surgery"},"publishedOn":"2026-03-22 15:58:22","publishedOnDateReadable":"March 22nd, 2026"},"versionCreatedAt":"2025-09-09 09:38:55","video":"","vorDoi":"10.1007/s11695-026-08594-5","vorDoiUrl":"https://doi.org/10.1007/s11695-026-08594-5","workflowStages":[]},"version":"v1","identity":"rs-7387810","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7387810","identity":"rs-7387810","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}