The Significant Effect of Diabetes Duration on Coronary Heart Disease Mortality: The Framingham Heart Study

Abstract

OBJECTIVE - The risk of coronary heart disease (CHD) in type 2 diabetes is two- to three-fold higher than in the general population, but the effect of diabetes duration on CHD risk has not been well characterized. We hypothesized that duration of diabetes is an important predictor of incident CHD among people with diabetes. RESEARCH DESIGN AND METHODS - The duration of diabetes (fasting glucose ≥126 mg/dl, random glucose ≥200 mg/dl, or use of an oral hypoglycemic agent or insulin) was assessed in participants with diabetes in the original and offspring cohorts of the Framingham Heart Study. Only subjects with diabetes diagnosed between the ages of 30 and 74 years, without a history of ketoacidosis, and free of cardiovascular disease at the baseline evaluation were included. Cox proportional hazards models were used to estimate the hazard ratio of incident CHD events and mortality over a 12-year follow-up period; models were adjusted for known CHD risk factors. RESULTS - Among 588 person-exams with diabetes (mean age 58 ± 9 years, 56% men), there were 86 CHD events, including 36 deaths. After adjustment for age, sex, and CHD risk factors, the risk of CHD was 1.38 times higher for each 10-year increase in duration of diabetes (95% CI 0.99-1.92), and the risk for CHD death was 1.86 times higher (1.17-2.93) for the same increase in duration of diabetes. CONCLUSIONS - Duration of diabetes increases the risk of CHD death independent of coexisting risk factors. Further research is necessary to understand the pathophysiology of this increased risk.