Cancer in patients admitted to hospital with diabetes mellitus aged 30 years and over: record linkage studies

The aim of this study was to determine the risk of cancer in people admitted to hospital for diabetes mellitus when aged 30 or older. This study involved the analysis of two statistical datasets of linked hospital and mortality data, in an area in southern England, between 1963 and 1998 (the Oxford Record Linkage Study, ORLS1) and between 1999 and 2008 (ORLS2). Rates of cancer in the diabetes cohorts were compared with rates of cancer in reference cohorts and expressed as rate ratios. The rate ratio for all cancer in people admitted to hospital with diabetes was 1.01 (95% CI 0.95-1.06, based on 15,898 people with diabetes) for the years 1963-1998; and 1.09 (1.00-1.19, based on 7,771 people with diabetes) in the years 1999-2008. In both datasets, there were significantly high rate ratios for cancers of the liver (ORLS1 and ORLS2, respectively, 2.0 [95% CI 1.4-2.9]; 2.5 [95% CI 1.3-4.3]), pancreas (2.2 [95% CI 1.8-2.7]; 3.5 [95% CI 2.5-4.8]) and uterus (1.5 [95% CI 1.0-2.2]; 2.6 [95% CI 1.4-4.5]). There were significantly low rate ratios for cancer of the prostate (0.6 [95% CI 0.5-0.7]; 0.7 [95% CI 0.5-0.9]) and non-melanoma skin cancer (0.6 [95% CI 0.5-0.8]; 0.8 [95% CI 0.6-0.96]). Diabetes mellitus was associated with an elevated risk of some site-specific cancers and a reduction of risk of others. Considering the risk in diabetes of all cancers combined, the elevation of risk, if any, is likely to be small and numerically less important than other known complications of diabetes.