Age at type 2 diabetes diagnosis and cause–specific mortality: Observational study of primary care patients in England

Objective: To examine the associations between age at type 2 diabetes diagnosis and the relative and absolute risk of all–cause and cause–specific mortality in England.

Research Design and Methods: In this cohort study using primary care data from the Clinical Practice Research Datalink, we identified 108,061 individuals with newly diagnosed type 2 diabetes (16-50 years of age), matched to 829,946 individuals without type 2 diabetes. We estimated all–cause and cause–specific mortality (cancer, cardiorenal, other [noncancer/cardiorenal]) by age at diagnosis, using competing risk survival analyses adjusted for key confounders.

Results: Comparing individuals with vs without type 2 diabetes, the relative risk of death decreased with an older age at diagnosis: the hazard ratio for all–cause mortality was 4.32 (95% CI: 3.35 to 5.58) in individuals diagnosed at 16–27 years compared to 1.53 (1.46 to 1.60) at 48–50 years. Smaller relative risks by increasing age at diagnosis were also observed for cancer, cardiorenal, and noncancer/cardiorenal death. Irrespective of age at diagnosis, the 10–year absolute risk of all–cause and cause–specific mortality was higher in individuals with type 2 diabetes; yet, the absolute differences were small.

Conclusions: Although the relative risk of death in individuals with vs without type 2 was higher at younger ages, the 10–year absolute risk of all investigated causes of death was small and similar in the two groups. Further multidecade studies could help estimate the long-term risk of complications and death in individuals with early-onset type 2 diabetes.