Insulin secretion and insulin sensitivity in Japanese patients with type 2 diabetes: a cross-sectional study comparing the homeostasis model assessment-2 (HOMA2) indexes and indexes derived from the oral glucose tolerance test

We analyzed the results of a 75-g oral glucose tolerance test in 731 drug-naive Japanese men with type 2 diabetes mellitus (T2DM) with fasting plasma glucose values ranging between 126 and 199 mg/dl. We then determined the index of insulin sensitivity and insulin secretion across the entire range of glucose loading. Next, we examined the correlation between these indexes and the homeostasis model assessment-2 (HOMA2) indexes, which can be calculated from the fasting serum glucose and insulin levels. HOMA2-S, the reciprocal index of HOMA2-IR, exhibited an excellent correlation with the insulin sensitivity index proposed by Matsuda and Defronzo (ISIMatsuda). HOMA2-B exhibited a good correlation with the insulin area under the curve (AUC) for the glucose AUC ratio for 0 to 120 min (InsAUC120/GluAUC120). In Japanese T2DM men, HOMA2-S and HOMA2-B can be used as rough estimates of ISIMatsuda and InsAUC120/GluAUC120, respectively. As the HOMA2-S and HOMA2-B scores obtained from these patients were correlated with the body mass index (BMI), we created charts showing the distribution of the HOMA2 index according to the serum glucose category and the BMI category.