Risk assessment by post-challenge plasma glucose, insulin response ratio, and other indices of insulin resistance and/or secretion for predicting the development of type 2 diabetes

Abstract

Objective: To find useful indices to identify subjects at high risk for developing diabetes. Methods: We retrospectively reviewed 75-g oral glucose tolerance test (OGTT) surveys conducted during 180 to 2001 in a Japanese community. Using personal charts of the surveys, 230 non-diabetics were followed for progression to type 2 diabetes. The usefulness of HbA1C, fasting (Glucose0) and 1-hour (Glucose60) glucose levels during OGTT, and indices for insulin resistance and/or secretion to identify high risk subjects for diabetes were then analyzed. Materials: Data described in personal charts of the OGTT program for residents of Nishikawa Town, Niigata Prefecture, Japan. Results: During the 4.3±2.7 years of follow-up, 52 subjects progressed to type 2 diabetes. Assessing glucose and insulin levels during OGTT, Glucose0, Glucose60, "Insulin Response Ratio" (IRR30, Insulin at 30 minutes/Fasting insulin; IRR60, insulin at 60 minutes/fasting insulin), and insulin secretion/insulin resistance index (ISIRI30) were significantly associated with progression to type 2 diabetes even after the result for OGTT, body mass index, and familial history of diabetes were adjusted. These were also able to identify still higher risk subjects for type 2 diabetes from those with impaired glucose tolerance (IGT) although other indices for insulin resistance or secretion and hemoglobin A1C were less contributable for this purpose. Conclusion: A combination of Glucose0 and Glucose60 can most cost effectively identify high risk subjects for type 2 diabetes from IGT. IRR30, IRR60 and ISIRI30 can also be used for such identification. However, further studies are needed to clarify whether these indices are superior to Glucose0 and Glucose60. © 2009 The Japanese Society of Internal Medicine.