Excess Mortality from Type 2 Diabetes: Rates and Risk Factors

Interactions among age, glycemic control, and kidney disease have a major influence on the risk of death for patients with type 2 diabetes, according to a study in the New England Journal of Medicine.

The researchers matched 435,369 patients with type 2 diabetes, drawn from the Swedish National Diabetes Register, to 2.1 million population control individuals without diabetes. Excess mortality associated with type 2 diabetes was analyzed, including the role of glycemic control and renal complications.

At a mean follow-up time of nearly 5 years in both groups, mortality was 17.7 percent in patients with type 2 diabetes versus 14.5 percent in control individuals. Excess mortality from type 2 diabetes was “historically low”: the adjusted hazard ratio (HR) for all-cause mortality was 1.15. Cardiovascular mortality was 7.9 percent versus 6.1 percent, respectively: HR 1.14.

For both all-cause and cardiovascular mortality, the risk increased with younger age, worse glycemic control, and more severe kidney complications. For diabetic patients under 55 with a glycated hemoglobin level of 6.9 percent or less, the HR for death of any cause was 1.92, compared with control individuals. By contrast, for patients 75 or older at the same level of glycemic control, all-cause mortality was somewhat lower than in control individuals: HR 0.95.

For patients younger than 55 with normoalbuminuria and a glycated hemoglobin level of 6.9 percent or less, the HR for death was 1.60, compared with control individuals. Again, older diabetic patients with normoalbuminuria and good glycemic control had lower all-cause mortality than did control individuals: HR 0.76 for patients 75 or older and 0.87 for those 65 to 74.

The data suggest wide variation in excess mortality among patients with type 2 diabetes, based on age, glycemic control, and renal complications. Patients under age 55 are at substantially higher risk even if they have good glycemic control and normoalbuminuria.

Discussing the implications for efforts to reduce excess mortality among patients with type 2 diabetes, the authors highlight the importance of reducing renal complications in all age groups. They write, “[E]xcess mortality among younger patients with chronic kidney disease was approximately 15 times as high as that in controls” [Tancredi M, et al. Excess mortality among persons with type 2 diabetes. N Engl J Med 2015; 373:1720–1732].