Assessment of insulin sensitivity (SI) and glucose effectiveness (SG) from a standardized hyperglucidic breakfast test in type 2 diabetics exhibiting various levels of insulin resistance

We investigated the measurement of insulin sensitivity (S (I)) with a standardized hyperglucidic breakfast (SHB) compared to minimal model analysis of an intravenous glucose tolerance test (S (I)-IVGTT) in 17 patients clinically referred as type 2 diabetics, not yet treated by insulin, and representing a wide range of body mass index and S (I). To classify the patients, ten meal-tolerance test-based calculations of S (I) (MTT-S (I)) were compared to S (I)-IVGTT, and their reference values and distribution were measured on a separate sample of 200 control SHBs and 209 control IVGTTs. Eight MTT-S-I indices exhibit significant correlations with S (I)-IVGTT: Mari's OGIS index, BIGTT-SI|(0-30-120), BIGTT-SI|(0-60-120,) 1/G (b) I (m), Caumo's oral minimal model (OMM), Sluiter's index "A" = 10(4)/(I (p)center dot G (p)), Matsuda's composite index given by the formula ISIcomp = 10(4)/(I (b) G (b) I (m) G (m))(0.5), S (I) = 1/I (b) G (b) I (m) G (m) with r (2) ranging between 0,53 and 0,28. S (I)-IVGTT and S (I)-MTT exhibited in the lower range a very different (non-normal) pattern of distribution and thus the cutoff value for defining insulin resistance varied among indices. With such cutoffs, S (I)-MTT < 6.3 min(-1)/(mu U/ml) 10(-4) with Caumo's OMM was the best predictor of insulin resistance defined as S (I)-IVGTT < 2 min(-1)/(mu U/ml) 10(-4). Other indices, including OGIS and BIGTT, resulted in more misclassifications of patients. HOMA-IR and QUICKI were poor predictors. The formula satisfactorily predicts IVGTT-derived glucose effectiveness in type 2 diabetics. Thus, SHB appears suitable for the measurement of S (I) and S (G) in type 2 diabetics, and the OMM seems to provide the most accurate SHB-derived index in this population.