Mortality in type 2 diabetes mellitus: magnitude of the evidence from a systematic review and meta-analysis

Abstract

Background: Type 2 diabetes is associated with an increase in age-related mortality. A systematic review and meta-analysis were performed to define the relative risks (RR) of all-cause or cause-specific mortality in type 2 diabetes and to determine gaps in current research. Methods: A comprehensive literature search was undertaken for studies (published 1990–2010) on mortality in type 2 diabetes. The study reports on the measure of mortality as defined by RR for all-cause and cause-specific mortality, heterogeneity, sensitivity analyses and biases. Results: In total 35 studies (220,689 patients; mean follow-up of 10.7 years) were eligible for inclusion: 33 studies reported increased mortality risks; 24 had full data on 95% confidence intervals (CIs), one study reported no excess mortality in men diagnosed after 65 years whereas three reported increased mortality in similar age groups in both sexes. Meta-analysis showed RR = 1.85 (95% CI 1.79–1.92) for all-cause mortality [men RR=1.57 (95% CI 1.46–1.68); women RR=2.0 (95% CI 1.89–2.12)], RR=1.76 (95% CI 1.66–1.88) for cardiovascular mortality and RR=2.26 (95% CI: 1.7-3.02) for stroke. There was no statistically significant evidence of publication bias. Conclusion: Type 2 diabetes increases mortality approximately two-fold increase and macrovascular disease is the principal cause of death.