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 or cardiorenal]) by age at diagnosis, using competing-risk survival analyses adjusted for key confounders.

Results: Comparing individuals with versus 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 3.35-5.58) in individuals diagnosed at ages 16-27 years compared with 1.53 (95% CI 1.46-1.60) at ages 48-50 years. Smaller relative risks by increasing age at diagnosis were also observed for cancer, cardiorenal, and noncancer or cardiorenal death. Irrespective of age at diagnosis, the 10-year absolute risk of all-cause and cause-specific mortality were higher in individuals with type 2 diabetes; yet, the absolute differences were small.

Conclusions: Although the relative risk of death in individuals with versus 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.