https://diabetes.acponline.org/archives/2015/11/13/2.htm

Mortality in diabetes may vary greatly by age, glycemic control, renal complications

Patients who were under age 55 faced a more substantial increase in mortality risk from having diabetes than older patients.


Mortality risk among people with type 2 diabetes varied greatly, including substantially increased risks with worse glycemic control, impaired renal function, and younger age, a study found.

Researchers in Sweden assessed risks among people with type 2 diabetes who were in the Swedish National Diabetes Register by Jan. 1, 1998. For each patient, 5 controls were randomly selected from the general population and matched by age, sex, and county. All the participants were followed until Dec. 31, 2011, in the Swedish Registry for Cause-Specific Mortality. 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, compared to 306,097 of 2,117,483 controls (14.5%) (adjusted hazard ratio [HR], 1.15; 95% CI, 1.14 to 1.16). The rate of cardiovascular death was 7.9% among diabetic patients versus 6.1% among controls (adjusted HR, 1.14; 95% CI, 1.13 to 1.15). Results appeared in the Oct. 29 New England Journal of Medicine.

The increase in mortality seen with diabetes increased with HbA1c. Among patients with HbA1c ≥9.7% who were younger than 55 years old, the HR for death from any cause compared to controls was 4.23 (95% CI, 3.56 to 5.02) and the HR for cardiovascular death was 5.38 (95% CI, 3.89 to 7.43). Among patients 75 years of age or older in this HbA1c category, the corresponding HR for death from any cause was 1.55 (95% CI, 1.47 to 1.63) and the HR for cardiovascular death was 1.42 (95% CI, 1.32 to 1.53).

The decrease in risk difference with older age was a continuing pattern. In diabetes patients under age 55 years with an HbA1c of 6.9% or less and normoalbuminuria, the HR for death compared with controls was 1.60 (95% CI, 1.40 to 1.82); the corresponding HR among patients 75 years of age or older was 0.76 (95% CI, 0.75 to 0.78), and diabetic patients 65 to 74 years of age also had a significantly lower risk of death (HR, 0.87; 95% CI, 0.84 to 0.91).

Renal function was also associated with mortality risk. Across the different age categories (younger to older), the HRs for death from any cause associated with diabetes ranged from 2.61 to 1.04 among patients with microalbuminuria, from 3.78 to 1.40 among those with macroalbuminuria, and from 14.63 to 3.31 among those with stage 5 chronic kidney disease.

No interaction was seen between diabetes and sex for all-cause mortality (P=0.21) or cardiovascular mortality (P=0.67). There was a time interaction, in which the risk of death from any cause among patients with diabetes as compared with controls was significantly lower during the last 7 years of follow-up (2005 or later) than during the first 7 years of follow-up (before 2005). Similar results were found for cardiovascular mortality.

The authors wrote, “… [I]n younger patients with type 2 diabetes, strict control of blood pressure, prescription of statins, targeting of good glycemic control, and avoidance of microalbuminuria are probably not enough to reduce excess mortality to the rate in the general population. Smoking cessation, increased physical activity, and the development of new cardiovascular-protective drugs, such as alternative lipid-lowering medications for persons who cannot take statins, may further improve outcomes in younger patients. Reducing the risk of renal complications in all age groups is highly important; the excess mortality among younger patients with advanced chronic kidney disease was approximately 15 times as high as that among controls.”