Background: Insulin resistance is an important factor in the pathogenesis of type 2 diabetes mellitus and other diseases, collectively known as "metabolic syndrome". The gold standard in measuring insulin resistance is glucose clamp, but this method is difficult to apply in large studies. Therefore, indirect indices of insulin sensitivity are proposed. The aim of the present study was to compare these simple indices with data from clamp studies.
Material/methods: We examined 51 obese subjects, 23 with impaired glucose tolerance (IGT), 28 with normal (obese-NGT), and 37 healthy lean controls. Insulin sensitivity was determined with the euglycemic hyperinsulinemic clamp technique. We estimated indices of insulin sensitivity: fasting plasma insulin (INS), logarithm INS (log [INS]), homeostasis model assessment (HOMA), logarithm HOMA (log [HOMA]) and quantitative insulin sensitivity check index (QUICKI).
Results: With clamp technique, we demonstrated a decrease in insulin sensitivity in both obese groups vs controls, and also in IGT compared to NGT subjects. The differences were significant when we used other indices of insulin sensitivity, except those for INS, log [INS] and HOMA between the two obese groups. Indirect indices correlated with insulin sensitivity derived from clamp in the whole population and in the subgroups of control and NGT-obese subjects. In the IGT group, only the correlations with log [INS], log [HOMA] and QUICKI were significant.
Conclusions: Simple indices may give valuable information about insulin sensitivity in large studies. Indices based on log-transformed plasma glucose and insulin levels are recommended in subjects with IGT.