Cancer risk in people with diabetes: Does physical activity and adiposity modify the association? Prospective data from the HUNT Study, Norway

Abstract

Aims: To examine whether physical activity and adiposity modify the increased risk of cancer associated with diabetes.

Methods: We prospectively examined the association of diabetes and risk of cancer among 73,726 persons stratified by physical activity and body mass index (BMI). Adjusted hazard ratios (HRs) with 95% confidence intervals (CI) were estimated from Cox regression.

Results: During a median follow-up of 22.0 years, 9572 people were diagnosed with incident cancer. There was no clear association between diabetes and cancer risk in those reporting high levels of physical activity (≥2.0h per week) (HR 0.93; 95% CI: 0.70-1.24) or those with a normal weight (BMI <25kg/m²) (HR 1.02; 95% CI: 0.84-1.25). However, among people with diabetes who reported low levels of physical activity (<2.0h per week), diabetes was associated with an HR of 1.15 (95% CI: 1.01-1.31). Correspondingly, diabetes was associated with an HR of 1.21 (95% CI: 1.07-1.37) among overweight or obese people (BMI ≥25kg/m²).

Conclusions: There was evidence that the increased risk of cancer associated with diabetes was confined to persons who reported low levels of physical activity, or who were overweight or obese.

Keywords: Body mass index; Cancer risk; Diabetes; Epidemiology; Leisure time physical exercise.