Diabetes-related risk factors and survival among individuals with type 2 diabetes and breast, lung, colorectal, or prostate cancer.

ABSTRACT

Premature death in diabetes is increasingly caused by cancer. The objectives were to estimate the excess mortality when individuals with type 2 diabetes(T2D) were diagnosed with cancer, and to examine the impact of modifiable diabetes-related risk factors. This longitudinal nationwide cohort study included individuals with T2D registered in the Swedish National Diabetes Register between 1998-2019. Poisson models were used to estimate mortality as a function of time-updated risk-factors, adjusted for sex, age, diabetes duration, marital status, country of birth, BMI, blood pressure, lipids, albuminuria, smoking, and physical activity. We included 690,539 individuals with T2D and during 4,787,326 person-years of follow-up 179,627 individuals died. Overall, the all-cause mortality rate ratio was 3.75 [95%confidence interval(CI)3.69-3.81] for individuals with T2D and cancer compared to those remaining free of cancer. The most marked risk factors associated to mortality among individuals with T2D and cancer were low physical activity, 1.59 (1.57-1.61) and smoking, 2.15 (2.08-2.22), whereas HbA1c, lipids, hypertension, and BMI had no/weak associations with survival. In a future with more patients with comorbid T2D and cancer diagnoses, these results suggest that smoking and physical activity might be the two most salient modifiable risk factors for mortality in people with type 2 diabetes and cancer.