Sex-specific relevance of diabetes to occlusive vascular and other mortality: Meta-analysis of individual data from 68 prospective studies with 77,000 deaths among 1 million adults
Background Several studies have shown that diabetes confers a higher relative risk of vascular mortality among women compared to men, but whether this exists across age groups and within levels of other risk factors is uncertain. Methods Individual data were obtained on 980,793 adults in 68 prospective studies. Cox models assessed the relevance of diabetes to occlusive vascular mortality (ischaemic heart disease, ischaemic stroke or other atherosclerotic deaths) by age, sex and other major vascular risk factors, and were also used to assess whether the associations of blood pressure, total cholesterol and body-mass index (BMI) to occlusive vascular mortality are modified by diabetes. Results During 9.8 million person-years of follow-up at ages 35-89 years, 19,686/76,965 (26%) deaths were attributed to occlusive vascular disease. Even after controlling for major vascular risk factors, diabetes conferred a doubling in occlusive vascular mortality risk among men (death rate ratio, RR=2·10; 95% CI 1·97-2·24) and a tripling among women (3·00; 2·71-3·33). RRs were more extreme at younger than at older ages (2·60 [2·30-2·94] at ages 35-59 versus 2·01 [1·85-2·19] at ages 70-89, ptrend=0·0001), and, at all ages, were more extreme in women than in men. So, among women aged 35-59, diabetes conferred nearly 6-fold increased risk. Because the occlusive vascular mortality rates at any given age were generally higher among men than women, the absolute excess mortality rates associated with diabetes were similar for men versus women: 0.08 %/year (0.05-0.10) versus 0.05 %/year (0.03-0.07) at ages 40-59; and 0.91 %/year (0.77-1.05) versus 1.08 %/year (0.84-1.08) at ages 70-89, respectively. Total cholesterol, blood pressure and BMI each displayed continuous log-linear associations with occlusive vascular mortality that were similar among those with and without diabetes. Interpretation Independently of other major vascular risk factors, diabetes substantially increased vascular risk in both men and women. Lifestyle changes (to reduce smoking and obesity) and wide use of cost-effective medications (especially statins and BP-lowering drugs) are important among both men and women with diabetes, but may not reduce the relative excess risk of occlusive vascular disease in women with diabetes.</p
