Comparison of twenty indices of insulin sensitivity in predicting type 2 diabetes in Japanese Americans: The Japanese American Community Diabetes Study.

Aims: We compared 20 previously reported indices of insulin sensitivity derived from samples during an oral glucose tolerance test (OGTT) to determine which was best in predicting incident type 2 diabetes.

Methods: We prospectively followed 418 Japanese Americans without diabetes for 10-11 years. We compared ability to predict incident diabetes of 20 insulin sensitivity indices-9 based on fasting samples, 7 based on 2-h and/or fasting samples, and 4 based on multiple samples (0, 30, 60, 120 min) during an OGTT-by integrated discrimination improvement, category free net reclassification improvement, and area under the receiver operator characteristic curve.

Results: There were 95 incident cases of diabetes. The Cederholm and Gutt indices, requiring more than only fasting samples, were the best to predict incident diabetes as judged by integrated discrimination improvement (0.187, 0.184), category free net reclassification improvement (0.962, 1.030), and area under the receiver operator characteristic curve (0.864, 0.863, respectively). Fasting indices were clearly inferior to both the Cederholm and Gutt indices.

Conclusions: Among the 20 indices, the Cederholm and Gutt indices predicted diabetes best but the Gutt index may be preferable because it requires fewer samples during an OGTT.