INS and Insulin resistance: The homeostasis model assessment of insulin resistance (HOMA-IR) was used to estimate fasting insulin resistance.30 Insulin sensitivity was estimated by the Matsuda Index for participants with complete OGTT results and the composite insulin sensitivity index for those with data at 0 and 120 min.31 32 Insulin secretion was calculated as the C-peptide index, which was the ratio of the increment in C-peptide to glucose during the first 30 min of the OGTT.