In participants with diabetes, in whom only fasting concentrations of GIP and GLP-1 were available, no unadjusted associations between fasting incretin GIP (56 first incident cancers/228 controls; HR 1.09; 95% CI 0.84–1.42; p = 0.504) and fasting GLP-1 (54 first incident cancers/225 controls; HR 0.87; 95% CI 0.68–1.10; p = 0.248) and incident first cancer were observed but the numbers were small. This evidence concerns the gene GCG and cancer.