Type 2 diabetes, glycaemic traits and upper gastrointestinal cancer risk: a prospective cohort study

Background Type 2 diabetes (T2D) has been linked with site-specific upper gastrointestinal (UGI) cancers during the past decades, but associations are still inconclusive. This study aimed to determine the association between T2D, glycaemic traits (random blood glucose and HbA1c) and UGI cancer (oesophageal and gastric cancer).Methods In the present study, based on the large-scale prospective cohort of UK Biobank, we included 452 631 eligible participants. T2D was defined according to baseline self-report data, clinical data and biochemistry data. Random blood glucose and HbA1c were measured at baseline. Polygenic risk score was used to classify individuals into different UGI cancer genetic risks. Multivariable Cox regression models were used to estimate HRs and 95% CIs.Results During a median follow-up of 10.26 years (IQR: 9.47-10.97), 1392 incident UGI cancer cases were identified. T2D was significantly associated with a 44% increment in UGI cancer risk (95% CI 1.22 to 1.70, p<0.001). Moreover, per SD increase in random blood glucose and HbA1c was associated with 7% (95% CI 1.03 to 1.12, p<0.001) and 6% (95% CI 1.04 to 1.09, p<0.001) increased hazards of developing UGI cancer, respectively. Patients with T2D at high genetic risk had a 2.33-fold hazard of UGI cancer (95% CI 1.66 to 3.28, p<0.001), compared with non-T2D individuals at low genetic risk.Conclusion Our results indicate that T2D and elevated levels of glycaemic traits may be risk factors for incident UGI cancer. Individuals with a high genetic risk and T2D have a significantly increased risk of developing UGI cancer.