Age-specific impact of diabetes mellitus on the risk of cardiovascular mortality: An overview from the evidence for Cardiovascular Prevention from Observational Cohorts in the Japan Research Group (EPOCH-JAPAN)

Background: Diabetes mellitus is a strong risk factor for cardiovascular disease. However, the age-specific association of diabetes with cardiovascular risk, especially in the elderly, remains unclear in non-Western populations. Methods: A pooled analysis was conducted using 8 cohort studies (mean follow-up period, 10.3 years) in Japan, combining the data from 38,854 individual participants without history of cardiovascular disease. In all, 1867 of the participants had diabetes, defined based on the 1998 World Health Organization criteria. The association between diabetes and the risk of death from cardiovascular disease, coronary heart disease (CHD), and stroke was estimated using a stratified Cox model, accounting for variability of baseline hazard functions among cohorts. Results: During the follow-up, 1376 subjects died of cardiovascular disease (including 268 of coronary heart disease and 621 of stroke). Diabetes was associated with an increased risk of cardiovascular death after multivariable adjustment (hazard ratio [HR] 1.62; 95% confidence interval [CI], 1.35-1.94). Similarly, diabetes was a risk factor for CHD (HR 2.13; 95% CI, 1.47-3.09) and stroke (HR 1.40; 95% CI, 1.05-1.85). In the age-stratified analysis of the risk of cardiovascular death, the relative effects of diabetes were consistent across age groups (p for heterogeneity = 0.18), whereas the excess absolute risks of diabetes were greater in participants in their 70s and 80s than in younger subjects. Conclusions: The management of diabetes is important to reduce the risk of death from cardiovascular disease, not only in midlife but also in late life, in the Japanese population.