The impact of diabetes mellitus on mortality from all causes and coronary heart disease in women: 20 years of follow-up.

BACKGROUND Few data are available on the long-term impact of type 2 diabetes mellitus on total mortality and fatal coronary heart disease (CHD) in women. METHODS We examined prospectively the impact of type 2 diabetes and history of prior CHD on mortality from all causes and CHD among 121 046 women aged 30 to 55 years with type 2 diabetes in the Nurses' Health Study who were followed up for 20 years from 1976 to 1996. RESULTS During 20 years of follow-up, we documented 8464 deaths from all causes, including 1239 fatal CHD events. Compared with women with no diabetes or CHD at baseline, age-adjusted relative risks (RRs) of overall mortality were 3.39 (95% confidence interval [CI], 3.08-3.73) for women with a history of diabetes and no CHD at baseline, 3.00 (95% CI, 2.50-3.60) for women with a history of CHD and no diabetes at baseline, and 6.84 (95% CI, 4.71-9.95) for women with both conditions at baseline. The corresponding age-adjusted RRs of fatal CHD across these 4 groups were 1.0, 8.70, 10.6, and 25.8, respectively. Multivariate adjustment for body mass index and other coronary risk factors only modestly attenuated the RRs. Compared with nondiabetic persons, the multivariate RRs of fatal CHD across categories of diabetes duration (< or =5, 6-10, 11-15, 16-25, >25 years) were 2.75, 3.63, 5.51, 6.38, and 11.9 (P< .001 for trend), respectively. The combination of prior CHD and a long duration of clinical diabetes (ie, >15 years) was associated with a 30-fold (95% CI, 20.7-43.5) increased risk of fatal CHD. CONCLUSIONS Our data indicate that among women, history of diabetes is associated with dramatically increased risks of death from all causes and fatal CHD. The combination of diabetes and prior CHD identifies particularly high-risk women.