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 1980 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 HbA_1C, 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 A_1C 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.