One-hour plasma glucose concentration and the metabolic syndrome identify subjects at high risk for future type 2 diabetes

OBJECTIVE - To assess the efficacy of 1-h plasma glucose concentration and the metabolic syndrome in predicting future risk of type 2 diabetes. RESEARCH DESIGN AND METHODS - A total of 1,611 subjects from the San Antonio Heart Study, who were free of type 2 diabetes at baseline; who had plasma glucose and insulin concentrations measured at time 0, 30, 60, and 120 min during the oral glucose tolerance test (OGTT), and who had their diabetes status determined with an OGTT after 7-8 years of follow-up, were evaluated. Two models, based on glucose tolerance status, 1-h plasma glucose concentration, and presence of the metabolic syndrome, were tested in predicting the risk for type 2 diabetes at 7-8 years of follow-up. RESULTS - A cutoff point of 155 mg/dl for the 1-h plasma glucose concentration during the OGTT was used to stratify subjects in each glucose tolerance group into low, intermediate, and high risk for future type 2 diabetes. A model based upon 1-h plasma glucose concentration, Adult Treatment Panel (ATP) III criteria for the metabolic syndrome, and fasting plasma glucose, independent of 2-h plasma glucose, performed equally well in stratifying nondiabetic subjects into low, intermediate, and high risk for future type 2 diabetes and identified a group of normal glucose-tolerant subjects who were at very high risk for future type 2 diabetes. CONCLUSIONS - The plasma glucose concentration at 1 h during the OGTT is a strong predictor of future risk for type 2 diabetes. A plasma glucose cutoff point of 155 mg/dl and the III criteria for the metabolic syndrome can be used to stratify nondiabetic subjects into three risk groups: low, intermediate, and high risk.