A New Index of Insulin Sensitivity Obtained From the Oral Glucose Tolerance Test Applicable to Advanced Type 2 Diabetes

Matthews et al. (1) demonstrated that the homeostasis model assessment of insulin resistance (HOMA-IR) is closely correlated with the insulin sensitivity index assessed by euglycemic clamp in only a few patients with type 2 diabetes. Emoto et al. (2) and Bonora et al. (3) also reported that HOMA-IR provided a good correlation in the clamp studies in a relatively greater number of diabetic subjects. However, it has been recognized among some investigators that the HOMA-IR shows relatively low value when the insulin secretion decreases in patients with advanced type 2 diabetes, because the HOMA-IR is a product of fasting glucose and insulin levels. On the other hand, several investigators have recently proposed methods to assess insulin sensitivity using an oral glucose tolerance test (OGTT). Stumvoll et al. (4) disclosed that the OGTT can assess insulin sensitivity in nondiabetic subjects. Even in type 2 diabetes, an index proposed by Matsuda and DeFronzo (5) was correlated to clamp-derived insulin sensitivity. Although these parameters from the OGTT decrease with worsening of glucose tolerance, the values inversely increase once the total insulin secretion declined. They have not been fully validated in Japanese subjects, …