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 linked to hospital and mortality records. We used sex-stratified Royston-Parmar models with two time scales to estimate incidence rates of all cancers, the four commonest cancers in the UK (colorectal, lung, prostate, breast), and the obesity-related cancers (e.g., liver, ovary) between 1/1/1998 and 14/1/2019, by age and diabetes duration.

Results

During 1,089,923 person-years, 18,977 incident cancers occurred. At the same age, in men and women rates of all cancers 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 comparing 20 to 5 years of duration was 1.18 (95% CI: 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 body mass index, there was no association with duration at any level of body mass index.

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.