Family history of diabetes mellitus and risk of colorectal cancer: A nationwide cohort study.

Aims Studies have shown the association between personal history of diabetes mellitus (DM type 1/2) and risk of colorectal cancer (CRC). This study aims to find the association between the family history of diabetes and CRC risk. Methods This large nationwide cohort study leveraged data from several Swedish nationwide registers (follow-up: 1964-2018) to compare the risk using standardized incidence ratio (SIR). Results 11,784,567 individuals (668,348 with DM) were included and followed for up to 54 years (median = 28 years). Those with a personal history of DM had a 1.4-fold increased risk of CRC compared to those without DM (95 % CI: 1.39-1.45). However, the addition of a family history of DM in 1 FDR or ≥ 2 FDRs did not significantly alter the increased risk of early-onset or late-onset CRC. Conclusion Leveraging one of the world's largest family-disease datasets, our cohort study confirmed that personal history of diabetes is associated with an increased risk of colorectal cancer, but we did not find an association between a family history of diabetes and risk of colorectal cancer.