Trends in Diabetes Incidence: The Framingham Heart Study

Abstract

OBJECTIVE Obesity and type 2 diabetes continue to increase in prevalence in the U.S. Whether diabetes incidence continues to increase in recent times is less well documented. We examined trends in diabetes incidence over the previous four decades. RESEARCH DESIGN AND METHODS Framingham Heart Study participants ages 40–55 years and free of diabetes at baseline (n = 4,795; mean age 45.3 years; 51.6% women) were followed for the development of diabetes in the 1970s, 1980s, 1990s, and 2000s. Diabetes was defined as either fasting glucose ≥126 mg/dL or use of antidiabetes medication. Poisson regression was used to calculate sex-specific diabetes incidence rates for a 47-year-old individual in each decade. Rates were also calculated among obese, overweight, and normal weight individuals. RESULTS The annualized rates of diabetes per 1,000 individuals were 2.6, 3.8, 4.7, and 3.0 (women) and 3.4, 4.5, 7.4, and 7.3 (men) in the 1970s, 1980s, 1990s, and 2000s, respectively. Compared with the 1970s, the age- and sex-adjusted relative risks of diabetes were 1.37 (95% CI 0.87–2.16; P = 0.17), 1.99 (95% CI 1.30–3.03; P = 0.001), and 1.81 (95% CI 1.16–2.82; P = 0.01) in the 1980s, 1990s, and 2000s, respectively. Compared with the 1990s, the relative risk of diabetes in the 2000s was 0.85 (95% CI 0.61–1.20; P = 0.36). CONCLUSIONS In our community-based sample, the risk of new-onset diabetes continued to be higher in the 2000s compared with the 1970s. In the past decade, diabetes incidence remained steady despite the ongoing trend of rising adiposity.