1-Hour and 2-Hour Postload Glucose Level on Oral Glucose Tolerance Test and the Risk of Incident Metabolic Syndrome

Abstract

Background: Metabolic syndrome (MetS) increases the cardiometabolic risk even in nondiabetic patients. Previous studies have demonstrated that 1-hour postload glucose (PG) and 2-hour PG based on oral glucose tolerance test (OGTT) predicted cardiometabolic risk. However, it is still unclear whether and to what extent postload glucose is associated with the risk of MetS. Methods: A total of 5389 nondiabetic Koreans were dichotomized into normoglycemic (NG) groups and abnormal glycemic groups based on OGTT, including elevated 1-hour PG (155 to 199 mg/dL) and impaired glucose tolerance (IGT) (2-hour PG 140 to 199 mg/dL), and followed up for 10 years. Cox proportional hazard model was used to evaluate hazard ratios (HRs) with 95% CIs for incident MetS. Subgroups were determined by high or normal 1-hour PG (cutoff: 155 mg/dL) and 2-hour PG (cutoff: 140 mg/dL). Results: Compared with NG, the risk of MetS increased proportionally to the level of 1-hour PG and 2-hour PG, independently of the number of baseline metabolic components. Even within people with normoglycemia, elevated PG above specific levels (1-hour PG ≥115 mg/dL and 2-hour PG ≥100 mg/dL) was significantly associated with the increased risk of MetS. In subgroup analysis, adjusted HR for MetS was higher in the group with high 1-hour PG and normal 2-hour PG [1.53 (95% CI, 1.35 to 1.74)] than in the group with normal 1-hour PG and high 2-hour PG [1.32 (95% CI, 1.02 to 1.70)]. Conclusion: Elevated 1-hour PG and 2-hour PG significantly are associated with greater risk for MetS, and 1-hour PG was superior to 2-hour PG in predicting MetS.