INS and metabolic syndrome: The index produced low correlation with our regression dataset (r = 0.28, P<0.001), which is believed to be due to differences in the investigated cohorts; in our cohort of strictly overweight and obese subjects with the metabolic syndrome, a small but statistically significant difference was detected between fasting plasma insulin as measured on the study days when stable isotope experiments/clamps were performed as opposed to oGGT fasting insulin that was measured after an overnight fast following a carbohydrate challenge for 2 days (9.7±0.6 mU/L vs. 10.7±0.6, P = 0.044).