1. When compared to men with type 1 diabetes, women have a 37% greater excess risk of all-cause mortality
2. When compared to men with type 1 diabetes, women have twice the excess risk of fatal and nonfatal vascular events
Evidence Rating Level: 1 (Excellent)
Study Rundown: Type 1 diabetes is a common, chronic autoimmune disorder that affects men and women with an equal incidence. Despite this, sex differences in excess mortality have been documented. This meta-analysis is the first to quantify sex difference in all-cause mortality and cause-specific mortality associated with type 1 diabetes. Documentation of a clinically meaningful sex difference in risk holds implications for the development of focused management strategies. Differences in mortality between men and women with type 1 diabetes were assessed by all cause mortality, mortality from cardiovascular disease, renal disease, the combined outcomes of accident and suicide, cancer, and from incident coronary heart disease and stroke associated with type 1 diabetes. Excess risk for all-cause mortality was 37% higher in women than men with type 1 diabetes. In analysis for cause-specific mortality, women demonstrated a 154% greater excess event rate for coronary heart disease, a 44% excess risk of renal mortality, and a 27% greater excess event rate for fatal and non-fatal stroke when compared to men with type 1 diabetes. No significant sex difference in risk was found in the analysis for cancer, accident or suicide. The large number of patients included in this meta-analysis gives the ability to assess sex-specific associations for cause-specific outcomes. This study is limited by absence of standardization for case ascertainment and endpoint definition.
In-Depth [systematic review and meta-analysis]: This study assessed whether or not sex differences exist in mortality outcomes for men and women with type 1 diabetes. PubMed was searched for studies published between Jan. 1, 1966 and Nov. 26, 2014. Overall, 26 studies were included in this meta-analysis, representing 214,114 individuals and 15,273 events. Included studies reported sex-specific estimates of the standardized mortality ratio (SMR) or hazard ratios associated with type 1 diabetes, either for all cause or cause-specific outcomes. Sex-specific SMRs and their pooled ratio (rSMR) (women to men) for all cause mortality, for morality from cardiovascular disease, renal disease, the combined outcomes of accident and suicide, cancer, and from incident coronary heart disease and stroke associated with type 1 diabetes were analyzed.
Overall, the pooled rSMR (women to men) demonstrated a significantly greater excess risk of all-cause mortality in women with type 1 diabetes (rSMR 1.37, [95% CI 1.21–1.56], p<0.0001). Pooled rSMR for fatal renal disease was 1.44 ([1.02–2.05], p=0.0404) and for cardiovascular disease mortality 1.86 ([1.62–2.15], p<0.0001, I.=2.39%). For incident stroke, rSMR suggested increase risk for women at 1.37 (1.03–1.81). In analysis of incident coronary heart disease, the sex difference was more pronounced, with an rSMR of 2.54 (95% CI 1.80–3.60). No evidence of significant difference between women and men was found for cancer, or accident and suicide; rSMR (1.23, [95% CI, 0.79–1.98], p=0.32); rSMR 1.34 (0.97–1.84, p=0.073), respectively.
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