Cancer incidence among Finnish people with type 2 diabetes during 1989-2014

Diabetes and cancer are common diseases both with enormous impact on health burden globally. The increased risk of several types of cancer among people with type 2 diabetes mellitus has been indicated repeatedly. This study aimed at exploring and describing the association between type 2 diabetes and cancer incidence. A cohort of 428,326 people with type 2 diabetes was identified from the Finnish National Diabetes Register and followed up through a register linkage with the Finnish Cancer Registry for cancer incidence during 1988-2014. A total of 74,063 cases of cancer occurred in this cohort in 4.48 million person-years. This accounted for 16% more than the expected cancer incidence in the Finnish general population; the standardized incidence ratio (SIR) was 1.16 (95% confidence interval [CI] 1.15-1.16). There was a statistically significant excess of cancers of lip (SIR=1.40, CI=1.28-1.53), liver (SIR=2.44, CI=2.35-2.53), pancreas (SIR=1.75, CI=1.70-1.79), stomach (SIR=1.22, CI=1.18-1.26), colon (SIR=1.22, CI=1.19-1.25), gallbladder and bile ducts (SIR=1.29, CI=1.21-1.36), non-melanoma skin (SIR=1.18, CI=1.15-1.22), kidney (SIR=1.42, CI=1.37-1.47), bladder (SIR=1.17, CI=1.13-1.21), and thyroid (SIR=1.22, CI=1.12-1.31). There was a small statistically significant decrease in prostate cancer incidence (SIR=0.95, CI=0.93-0.96). This study showed an association between type 2 diabetes mellitus and the incidence of cancer at numerous sites in the Finnish population.