Body Mass Index and All-Cause, Cancer, and Cardiovascular Mortality in Adults Aged 16-50 Years With and Without Type...

To examine the association between body mass index (BMI) and risk of all-cause, cancer, and cardiovascular diseases (CVD) mortality among adults aged 16-50 years with and without type 2 diabetes (T2D).

We conducted a retrospective matched cohort study using primary care records from the Clinical Practice Research Datalink (CPRD) linked to Hospital Episode Statistics (HES) and Office for National Statistics (ONS) mortality records. Individuals aged 16-50 years with T2D were matched (1: up to 10) to those without T2D by year of birth, sex, and general practice. Using flexible parametric survival models and competing risk approaches, we estimated hazard ratios (HRs) and 10-year cumulative incidences of all-cause and cause-specific mortality adjusted for confounders.

A total of 384 787 individuals were included, of whom 86 606 (22.5%) lived with T2D (median age at diagnosis, 44.0 years). The associations between BMI and all-cause mortality, as well as cause-specific mortality, exhibited a U-shaped pattern, with the nadir occurring at a BMI of 29.3 kg/m² and 27.2 kg/m² in those with and without T2D, respectively. The highest absolute risk and the greatest risk differences between individuals with and without T2D were observed at lower BMI values. At 45 years and BMI of 20 kg/m², the 10-year cumulative incidence of all-cause mortality risk was 17.3% (95% CI: 13.9%, 20.6%) for individuals with T2D compared to 4.4% (95% CI: 4.0%, 4.7%) in those without.

The excess risk of mortality associated with T2D was greatest at lower BMI, where absolute risk estimates were high.