Duration of Type 2 Diabetes and Incidence of Cancer: An Observational Study in England.

Objective: To investigate the association between duration of type 2 diabetes and cancer incidence.

Research design and methods: In the Clinical Practice Research Datalink database, we identified 130,764 individuals with type 2 diabetes aged ≥35 years at diagnosis who were linked to hospital and mortality records. We used sex-stratified Royston-Parmar models with two timescales to estimate incidence rates of all cancers, the four commonest cancers in the U.K. (colorectal, lung, prostate, breast), and the obesity-related cancers (e.g., liver, ovary) between 1 January 1998 and 14 January 2019, by age and diabetes duration.

Results: During 1,089,923 person-years, 18,977 incident cancers occurred. At the same age, rates of all cancers in men and women did not vary across durations ranging from diagnosis to 20 years; conversely, for any duration, there was a strong, positive association between age and cancer rates. In men, the rate ratio (95% CI) comparing 20 with 5 years of duration was 1.18 (0.82-1.69) at 60 years of age and 0.90 (0.75-1.08) at 80 years; corresponding ratios in women were 1.07 (0.71-1.63) and 0.84 (0.66-1.05). This pattern was observed also for the four commonest cancers. For obesity-related cancers, although rates were generally higher in individuals with a higher BMI, there was no association with duration at any level of BMI.

Conclusions: In this study, we did not find evidence of an association between duration of type 2 diabetes and risk of cancer, with the higher risk observed for longer durations related to ageing.