The influence of insulin therapy on measurements of optical coherence tomography parameters in diabetic patients without retinopathy

Purpose To determine whether there was a change in the fundus of the eye in diabetic patients without retinopathy after insulin therapy. Methods The diabetic patients without retinopathy were included in this study. A swept-source optical coherence tomography/angiography (SS-OCT/A) was used to obtain the measurements of macular retinal nerve fibre layer (mRNFL) thickness, ganglion cell-inner plexiform layer (GC-IPL) thickness, retinal thickness (RT), macular choroidal thickness (MCT), peripapillary retinal nerve fibre layer (pRNFL) thickness, peripapillary choroidal thickness (PCT), and perfused vascular density (PVD). Univariable and multivariable regression analyses were performed to explore the influence of insulin use on measurements of OCT/A. Results A total of 1140 patients used insulin (using group), and 126 patients did not use insulin (without group). The average MCT of the using group was 171.3±67.8 μm, which was thinner than that in the without group (190.2±74.7 μm) (P=0.012). The average PVD of the using group (48.0±2.1 μm) was less than that in the without group (48.7±2.1 μm) (P<0.001). After adjusting for age, gender, axial length, duration, HbA1c, systolic blood pressure, diastolic blood pressure, cholesterol, serum creatinine, insulin use was significantly associated with thinner MCT (beta=-16.12μm; 95%CI:-29.42, −2.81μm; P= 0.018) and lower PVD (beta=-0.79; 95%CI: −1.22, −0.36; P<0.001). Conclusion The use of insulin by diabetic patients without retinopathy might decrease the MCT and PVD compared to patients who did not use insulin, which helps to better understanding the role of insulin use on higher risk for diabetic retinopathy.