Excess Mortality among Persons with Type 2 Diabetes

Abstract

Background: The excess risks of death from any cause and death from cardiovascular causes among persons with type 2 diabetes and various levels of glycemic control and renal complications are unknown. In this registry-based study, we assessed these risks according to glycemic control and renal complications among persons with type 2 diabetes.

Methods: We included patients with type 2 diabetes who were registered in the Swedish National Diabetes Register on or after January 1, 1998. For each patient, five controls were randomly selected from the general population and matched according to age, sex, and county. All the participants were followed until December 31, 2011, in the Swedish Registry for Cause-Specific Mortality.

Results: The mean follow-up was 4.6 years in the diabetes group and 4.8 years in the control group. Overall, 77,117 of 435,369 patients with diabetes (17.7%) died, as compared with 306,097 of 2,117,483 controls (14.5%) (adjusted hazard ratio, 1.15; 95% confidence interval [CI], 1.14 to 1.16). The rate of cardiovascular death was 7.9% among patients versus 6.1% among controls (adjusted hazard ratio, 1.14; 95% CI, 1.13 to 1.15). The excess risks of death from any cause and cardiovascular death increased with younger age, worse glycemic control, and greater severity of renal complications. As compared with controls, the hazard ratio for death from any cause among patients younger than 55 years of age who had a glycated hemoglobin level of 6.9% or less (≤52 mmol per mole of nonglycated hemoglobin) was 1.92 (95% CI, 1.75 to 2.11); the corresponding hazard ratio among patients older than 75 years of age or older was 0.95 (95% CI, 0.94 to 0.96). Among patients with normoalbuminuria, the hazard ratio for death among those younger than 55 years of age with a glycated hemoglobin level of 6.9% or less, as compared with controls, was 1.60 (95% CI, 1.40 to 1.82); the corresponding hazard ratio among patients older than 75 years of age or older was 0.76 (95% CI, 0.75 to 0.78), and patients 65 to 75 years of age also had a significantly lower risk of death (hazard ratio, 0.87; 95% CI, 0.84 to 0.91).

Conclusions: Mortality among persons with type 2 diabetes, as compared with that in the general population, varied greatly, from substantial excess risks in large patient groups to lower risks of death depending on age, glycemic control, and renal complications. (Funded by the Swedish government and others.).