The Comparison of Glycated Hemoglobin and Homeostasis Model Assessment Values to 30, 60 and 90-Min Glucose Levels During OGTT in Subjects with Normal Glucose Tolerance

Abstract

Abstract Background: The subjects with impaired glucose tolerance have an increased risk for future type 2 diabetes (T2DM); however, a significant number of individuals who develop T2DM have normal glucose tolerance (NGT) at baseline. The study aims to compare glycated hemoglobin (HbA1C) and homeostasis model assessment (HOMA-IR) levels to 30, 60 and 90-min glucose levels in subjects with NGT. Methods: A 75-g oral glucose tolerance test (OGTT) at 0, 30, 60, 90 and 120-min was performed in 1118 subjects without known T2DM. Blood samples were also drawn for fasting insulin and HbA1C levels. Results: Forty percent of the subjects with NGT had increased post-challenge values above the determined optimal glucose levels (10.2, 10.3 and 8.9 mmol/L at 30, 60 and 90-min, respectively). Compared to the subjects with NGT whose glucose levels were below the determined optimal values at 30, 60 and 90-min, we found significantly elevated HbA1C and HOMA-IR levels in the subjects with NGT whose glucose levels were above the determined optimal values (p<0.001). Conclusions: We conclude that the subjects with NGT have different HbA1C and HOMA-IR levels considering glucose levels measured earlier than at 2-h during OGTT. Further well-designed prospective studies are needed to define the significance of 30-min, 60-min and 90-min glucose levels in the prediction of disease in subjects with T2DM.