Association of insulin indices and glucose tolerance test during pregnancy in South Indian women

Background: Gestational diabetes (GDM) is on the rise in Asia. High Insulin resistance (IR), low insulin sensitivity (IS) and pancreatic cell dysfunction are said to be responsible. This can be detected by estimating insulin indices along with oral glucose tolerance test (OGTT). Objective: The aim was to correlate the various Insulin indices and OGTT values in pregnant women. Material and Methods: This cross sectional study included 69 pregnant women between 24 to 28 weeks of gestation who underwent 3 hour 100-g OGTT along with insulin levels. They were stratified into: Normal glucose tolerance (NGT), gestational impaired glucose tolerance (GIGT) and GDM based on Carpenter and Coustan criteria. The insulin indices studied were Matsuda Index, quantitative insulin sensitivity check index (QUICKI), homeostasis model assessment for IS (HOMA-1S, HOMA2-S), HOMA-1IR, HOMA2-IR for resistance & (HOMA1-B, HOMA2-B) for Insulin secretion. Results: The prevalence of GDM in this study was 13% and that of GIGT was 11%. Lower IS indices (Matsudo Index, QUICKI, HOMA1-S, HOMA2-S) and higher IR (HOMA1-IR, HOMA2-IR) were seen in the GDM & GIGT groups. Matsuda Index at the cut offvalue of =2.2 showed superior diagnostic ability (sensitivity 88.24%, specificity 80.77%), and had the maximum AUC (area under curve). No statistically significant differences in ß-cell secretion were noted in the three groups. Conclusions: Low IS and high IR rather than defective insulin secretion seemed to be responsible for altered OGTT in this study group. The Matsuda index for IS and HOMA1 IR for resistance seemed better than other insulin indices.