Background Type 2 Diabetes Mellitus (T2DM) and cancer are diseases of increasing prevalence whose complications are related to decreased productivity, quality of life and survival. Recent studies suggest association of type 2 diabetes mellitus with cancer of breast, colon, prostate and others. Early diagnosis and proper treatment of these diseases could minimise the high costs for the public health as well as prevent severe complications and sequelae.

Methods Secondary information about hospital admissions in 34 hospitals of Ribeirao Preto/Brazil and 26 other cities were obtained from records of the Center for Data Processing linked to the Department of Social Medicine of Faculty of Medicine of Ribeirao Preto/University of Sao Paulo. The study was approved by the Ethics Committee of HCFMRP/USP.

Results Data of 772.659 hospitalisations which happened from 1998 to 2007 were collected and 70 184 (9.1%) of them were due to malignant neoplasms; 45 167 (5.8%) were due to T2DM and 2204 (0.3%) were of patients with both, malignant disease and T2DM. The mean age was 61.3 (±13.4), 63.5 (±12.6) and 65.9 years (±11.4) respectively. 21% of admissions happened in university hospital of FMRP/USP. The PR of admissions by T2DM and neoplasms was 0.48 with a CI 95% [PR 0.48 (95% CI 0.46 to 0.50)] p<0.05. Subsequent case-control study has shown similar results [(OR 0.40 (95% CI 0.28 to 0.56)] p<0.05.

Conclusion These findings suggest a lower chance of hospitalisation of patients with diagnosis of T2DM and associated cancer. Currently a study to clarify these findings is underway.