Aims/hypothesis: The objective of this study was to use Scottish national data to assess the influence of type 2 diabetes on the risk of cancer at 16 different sites, while specifically investigating the role of confounding by socioeconomic status in the diabetes-cancer relationship.
Methods: All people in Scotland aged 55-79 years diagnosed with any of the cancers of interest during the period 2001-2007 were identified and classified by the presence/absence of co-morbid type 2 diabetes. The influence of diabetes on cancer risk for each site was assessed via Poisson regression, initially with adjustment for age only, then adjusted for both age and socioeconomic status.
Results: There were 4,285 incident cancers in people with type 2 diabetes. RR for any cancers (adjusted for age only) was 1.11 (95% CI 1.05, 1.17) for men and 1.33 (1.28, 1.40) for women. Corresponding values after additional adjustment for socioeconomic status were 1.10 (1.04, 1.15) and 1.31 (1.25, 1.38), respectively. RRs for individual cancer sites varied markedly.
Conclusions/interpretation: Socioeconomic status was found to have little influence on the association between type 2 diabetes and cancer.