One-hour postload plasma glucose concentration in people with normal glucose homeostasis predicts future diabetes mellitus: a 12-year community-based cohort study

Abstract

OBJECTIVE: In Caucasians, plasma glucose concentration at 1 h during an oral glucose tolerance test (OGTT) may be a better predictor of future diabetes mellitus than the fasting or 2-h postload glucose concentration. We investigated whether the 1-h glucose concentration could be used to predict future diabetes mellitus in Asian ethnicity. MEASUREMENTS: A total of 5703 Koreans with normal glucose tolerance were enrolled from the Korean Genome and Epidemiology Study. Indices of insulin sensitivity and beta-cell function estimated from standard 75-g OGTTs performed every 2 years for 12 years were used to identify whether the 1-h glucose concentration could predict future diabetes mellitus. RESULTS: The mean age and body mass index at baseline were 51.3 +/- 8.7 years and 24.2 +/- 3.0 kg/m(2) , respectively. During the 12-year follow-up, 593 subjects (10.3%) developed diabetes mellitus. The area under the receiver-operating characteristic curve for incident diabetes mellitus was higher for the 1-h postload glucose concentration than for the fasting or postload 2-h glucose concentration (0.74 vs 0.61 or 0.63). The cut-off value of >/=8.0 mmol/l identified incident diabetes mellitus with 70% sensitivity and 68% specificity. After adjusting for typical risk factors, subjects with a 1-h postload glucose concentration >/=8.0 mmol/l had lower beta-cell function and a 2.84-fold increased risk of incident diabetes mellitus compared with their counterparts. CONCLUSIONS: In this community-based 12-year prospective cohort study, 1-h postload plasma glucose concentration was an independent predictor of future diabetes mellitus and 8.0 mmol/l was suggested as a cut-off value.