Excess Body Weight and Cancer Risk in Patients with Type 2 Diabetes Who Were Registered in Swedish National Diabetes Register – Register-Based Cohort Study in Sweden

AIM: To assess the association between excess body weight and cancer risk in patients with type 2 diabetes (T2D) who were registered in the Swedish National Diabetes Register (NDR). METHODS: This is a cohort study based on 25,268 patients with T2D and baseline BMI≥18.5 kg/m(2) from NDR 1997–1999. Subjects were grouped according to BMI into normal weight (18.5 to 24.9), overweight (25 to 29.9) or obesity (30 or more). All subjects were followed until the first occurrence of cancer, or death, or the end of follow-up (December 31, 2009). Adjusted hazard ratios (HRs) and 95% confidence interval (CI) for cancer risks were estimated by Cox regression. RESULTS: In men with T2D, overweight was associated with increased risks of all cancer [1.13 (1.02–1.27)], gastrointestinal cancer [1.34 (1.07–1.72)] and colorectal cancer [1.59 (1.18–2.13)]; obesity was related to higher risks of all cancer [1.17 (1.04–1.33)], gastrointestinal cancer [1.40 (1.08–1.82)] and colorectal cancer [1.62 (1.17–2.24)]. In women with T2D, obesity was associated with increased risk of all cancer [1.30 (1.12–1.51)], gastrointestinal cancer [1.40 (1.03–1.91)] and postmenopausal breast cancer [1.39 (1.00–1.91)]. CONCLUSIONS: Excess body weight was associated with increased risks of all cancer, gastrointestinal cancer and colorectal cancer in men with T2D. Obesity was related with elevated risks of all cancer, gestational cancer and postmenopausal breast cancer in women with T2D.