Predictive Properties of Impaired Glucose Tolerance for Cardiovascular Risk Are Not Explained by the Development of Overt Diabetes During Follow-Up

Abstract

OBJECTIVE—To evaluate the relationship of impaired glucose tolerance (IGT) at baseline to coronary heart disease (CHD) incidence, and cardiovascular disease (CVD) and total mortality at follow-up, and to analyze whether the relationship is independent of the subsequent development of diabetes during follow-up. RESEARCH DESIGN AND METHODS—A baseline screening survey for diabetes was performed in 1987 using a 2-h 75-g oral glucose tolerance test. A total of 1,234 men and 1,386 women aged 45–64 years, who were free of diabetes at baseline, were followed up for 10 years. During the follow-up, 153 subjects had an incident CHD event, 224 died, and 100 deaths were due to cardiovascular causes. Multivariate adjusted (adjusted for age, sex, waist-to-hip ratio, systolic blood pressure, cholesterol, HDL cholesterol, and smoking) hazard ratio (HR) was estimated using Cox regression analysis. RESULTS—In subjects who had IGT at baseline and who did not progress to diabetes during the follow-up, the multivariate adjusted HR (95% CI) was 1.49 (0.95–2.34) for CHD incidence, 2.34 (1.42–3.85) for CVD mortality, and 1.65 (1.13–2.40) for all-cause mortality. CONCLUSIONS—Baseline IGT was an independent risk predictor for cardiovascular morbidity and mortality and for total mortality, which was not confounded by the subsequent development of overt diabetes.