gms | German Medical Science

Background: Epidemiological findings indicate that cancer risk in patients with type 2 diabetes (T2D) might be influenced by antidiabetic drugs. For this study a cohort of members of the disease management program (DMP) for type 2 diabetics was built. Data of this cohort was pseudonymised and then linked with cancer registry data of North Rhine-Westphalia to investigate risk factors of incident cancer in type 2 diabetics.

Methods: This first feasibility report uses data from 26,742 T2D patients, who were 40 to 79 years old, resided in the Muenster District, and who were enrolled between June 2003 and June 2008. Cancer cases were identified through the regional Cancer Registry by using probabilistic record linkage procedures and pseudonymised personal identifiers. Censoring date was December 31, 2008. We included only first cancers, leaving 12,650 male and 14,092 female T2D with a total of 88,778 person-years (py). We computed standardized incidence ratios (SIR) for external comparisons and we employed Cox regression models within the cohort.

Results: We identified 759 first cancers among male T2D patients (18.7 per 1,000 py) and 605 among females (12.7 per 1,000 py). The risk of any incident cancer in T2D was raised (SIR=1.14; 95% confidence interval [1.10–1.21]), in particular for cancer of the liver (SIR=1.94 [1.15-2.94]) and pancreas (SIR=1.45 [1.07-1.92]). SIRs decreased markedly with time after T2D diagnosis. In Cox models, adjusting for diabetes duration, body mass index and sex, insulin therapy was related to higher cancer risk (HR=1.19 [1.02–1.39]). No effect was seen for metformin.

Discussion: Our study demonstrates the feasibility of record linkage between DMP and cancer registries. The first results confirm findings in previous studies of diabetes and cancer. It is planned to expand this cohort by inclusion of further regions of the state, expansion of the follow-up times, and collection of a more detailed medication history.