Gastrointestinal cancer incidence in type 2 diabetes mellitus; results from a large population-based cohort study in the UK

•There is conflicting evidence on the incidences of gastrointestinal cancer types in type 2 diabetes mellitus.•Higher IRs of liver, pancreatic and colon cancer were found in patients with type 2 diabetes mellitus.•The lower observed IRs of oesophageal cancer in type 2 diabetic patients warrants further investigation. Patients with type 2 diabetes mellitus (T2DM) have been shown to have higher incidences of liver, pancreatic, and colorectal cancer compared to non-diabetic individuals. Current evidence is conflicting for other gastrointestinal (GI) cancers. Therefore, we aimed to determine incidence rates (IRs) of all GI cancers in patients with and without T2DM. A cohort study was performed using the UK Clinical Practice Research Datalink (1988-2012). A cohort of antidiabetic drug users was matched at baseline to a non-diabetic cohort, by age, sex, and practice. Crude IRs and 95% confidence intervals (95% CI) of GI cancers per 100,000 person-years were calculated stratified by age, sex, and calendar year. 333,438 T2DM and 333,438 non-diabetic individuals were analyzed. IRs of liver (IR 26, 95% CI 24–28 vs. 8.9, 95% CI 7.7–10), pancreatic (IR 65, 95% CI 62–69 vs. 31, 95% CI 28–34), and colon cancer (IR 119, 95% CI 114–124 vs. 109, 95% CI 104–114) were significantly higher in the diabetic compared to the non-diabetic cohort, whereas the IR of oesophageal cancer was significantly lower (IR 41, 95% CI 39–44 vs. 47, 95% CI 44–51). Sex-specific IRs of colon cancer remained significantly higher in men with T2DM, and IRs of esophageal cancer remained significantly lower in women with T2DM. In this study, T2DM patients were shown to have higher crude IRs of liver, pancreatic and colon cancer, but not of gastric, biliary, and rectal cancer. Moreover, the lower observed IRs of oesophageal cancer in diabetic patients warrants further investigation.