Comparison among different insulin sensitivity indices in obese patients.

AIMS: Recently, several indices have been proposed for the measurement of insulin sensitivity (IS). We set out to make a comparison between fasting insulin, and different IS indices in obese subjects. PATIENTS AND METHODS: Fasting and post load (75 g) glucose and insulin were measured in a consecutive series of 767 (626 F, 141 M) obese (body mass index > 30 kg/m(2)) out-patients, with no known history of diabetes (DM). Mean (+/- sd) age was 46.7 +/- 13.8 years in females and 45.6 +/- 14.3 years in males. Indices of IS based on fasting homeostasis assessment model (HOMA) and post-load (ISI) glucose and insulin and either parameter (1A, and 1B scores) were determined. RESULTS: DM was diagnosed in 21.4% of females, and 20.6% of males, and impaired glucose tolerance in 24% females and 21.3% males. Fasting and post-load glucose, triglyceride and HDL-cholesterol were correlated with all indices in both sexes (P < 0.05). The relative risk of different conditions in the upper quartile of ISI was similar to that observed in the upper quartile of HOMA. The HOMA index was similarly associated with low HDL-cholesterol and hypertriglyceridaemia as fasting insulin, while it showed a greater association with diabetes; ISI was similarly associated with all three conditions as the HOMA index. CONCLUSIONS: Indices of IS based on fasting glucose and insulin show a greater association with diabetes, but not with other abnormalities related to insulin resistance, when compared with fasting insulin levels. Indices based on post-load glucose and insulin do not offer any advantage over those based on fasting values.