All-cause mortality risk with type 1 diabetes may be greater in women vs. men

Women with type 1 diabetes may have a higher all-cause mortality risk than men with the condition, as well as higher risk for fatal and nonfatal vascular events, according to a recent study.

Researchers performed a systematic review and meta-analysis of studies published between Jan. 1, 1966, and Nov. 26, 2014, to determine whether sex differences were present in all-cause mortality and cause-specific outcomes in patients with type 1 diabetes. The authors calculated sex-specific standardized mortality ratios (SMRs) and pooled ratios of women to men for all-cause mortality and mortality from cardiovascular disease, renal disease, cancer, accident and suicide, and incident coronary heart disease and stroke associated with type 1 diabetes. The study results were published online Feb. 6 by Lancet Diabetes Endocrinology.

Overall, data from 26 studies (214,114 patients, 15,273 events) were included in the analysis. For all-cause mortality, the pooled women-to-men ratio of SMR was 1.37 (95% CI, 1.21 to 1.56). For incident stroke, fatal renal disease, and fatal cardiovascular disease, the pooled women-to-men mean ratio of SMR was 1.37 (95% CI, 1.03 to 1.81), 1.44 (95% CI, 1.02 to 2.05), and 1.86 (95% CI, 1.62 to 2.15). The authors found a more pronounced sex difference for incident coronary heart disease, with a pooled women-to-men ratio of SMR of 2.54 (95% CI, 1.80 to 3.60). No sex-related differences in mortality were noted for cancer or for accident and suicide. The authors concluded, “Women with type 1 diabetes have a roughly 40% greater excess risk of all-cause mortality, and twice the excess risk of fatal and nonfatal vascular events, compared with men with type 1 diabetes.”

The authors pointed out that many variables, such as study design and duration and definitions of end points, were not standardized among the included studies and that residual confounding probably affected their results, among other limitations. However, they concluded that “a significant and clinically meaningful sex difference exists” in excess risk for death, especially deaths from vascular causes, in women with type 1 diabetes compared with men. The authors said that more research in this area is needed to improve cardiovascular risk prediction methods. “Ultimately, an increased understanding and appreciation of sex differences in the effect of type 1 diabetes on vascular-related disease is likely to have profound clinical implications for how women with type 1 diabetes are treated and managed throughout their life course,” they concluded.

The author of an accompanying comment said that the study's findings support systematic improvements in glycemic control for all patients with type 1 diabetes through tailored therapy, as well as strategies to address undertreatment. The comment author also noted that it's uncertain how to decrease the excess mortality risk in women with type 1 diabetes since the reasons behind it are not clear. “Achievement of a reduction in the high type 1 diabetes mortality rates will need additional expenditure on the care of patients with the disorder, many of the benefits from which might not be seen for up to 20 years,” the comment author wrote. “The additional investment in the services and equipment to improve glycemic control must start now.”