Fasting GLP-1 was associated with lower risk of incident first cancer in participants without diabetes (HR 0.91, 95% CI 0.83–0.99; p = 0.048) when adjusted for age, sex, waist circumference, and smoking status but the association was attenuated when physical activity was entered upon Model 2b (p = 0.052; Supplementary Table S4). This evidence concerns the gene GCG and cancer.