LAUSR

Abstract Background: Beta cell exhaustion & insulin deficiency in Type 1 Diabetes mellitus has been associated with decreased retinal nerve fibre layer thickness due to absence of trophic effect of insulin on retinal nerve fibre layer (RNFL). It is expected that RNFL will be thickened in Type 2 diabetes mellitus (T2DM) because of compensatory hyperinsulinemia; however few studies have demonstrated RNFL degeneration in T2D patients. Hence, we investigated the changes in RNFL in states of excess insulin due to insulin resistance in patients of metabolic syndrome, pre-diabetes, newly diagnosed T2DM & obese polycystic ovarian disease (PCOD). Study Design: 40 patients who either were Pre-Diabetic or Obese PCOD Females or MetS (NCEP-ATP3) were selected for the study. Serum fasting Insulin were measured using Chemi-luminescence method & log (HOMA-IR) calculated. All the selected patients were thereafter subjected to 3-D Ocular Coherence Tomography & there RNFL thickness assessed at the posterior pole. Results: Fasting Insulin, HOMA-IR, Log (HOMA-IR) had significant positive correlation with RNFL thickness. After adjustment of all the confounders’ viz. age, waist circumference, sex, lipid parameters and BMI, only fasting insulin and log (HOMAIR) were found as significant predictors of retinal nerve fibre layer thickness. For every one unit increase in Fasting insulin and log (HOMAIR), nerve fibre layer thickness increases by 0.002 units and 0.008 units (keeping other variables constant). Conclusions: Apart from a being predominant vascular pathology, a neuro-degenerative process due to supply-consumption mismatch might be a plausible component of overt retinopathy. Obese diabetics might be more prone to retinal neuro-degeneration .Our study may also provide reliable baseline evidence to use retinal nerve fibre layer thickness as a non-invasive marker of insulin resistance.