OBJECTIVES: To study the association between Diabetes Mellitus (DM) and the incidence of Cancer, focusing on type-specific and sex-specific cancers.  METHODS: Study’s data were obtained from CSD LPD, an Italian General Practitioner’s longitudinal database. We have evaluated the risk of Cancer incidence among people with DM compared with those without this pathology, in patients who had no reported history of Cancer at the start of the follow-up on January 2006. For the DM group, patients with at least one diagnosis of DM and a GP contact from January - December 2005 have been selected, while for the DM free group, patients without a diagnosis of DM and a contact with the GPs in the same period have been selected. Both groups have been followed-up for 5 years. In order to evaluate an association between the presence of DM and the incidence of Cancer multivariate logistic models adjusted by age and sex have been implemented.  RESULTS: A total of 73.144 (6 %) patients with a diagnosis of DM and 1.119.652 (94%) patients  without DM diagnosis were selected.  During follow-up 8.824 and 82.477 incident cases of Cancer were documented from the DM and DM free groups respectively. Statistical analysis showed an Adjusted (age and sex) Odds Ratio of 1,06 (95% Cl 1,06-1,20) suggesting that patients with DM have a 6% increased risk of cancer incidence (all types). Regarding  type-specific cancer analysis the OR for Liver cancer (2,44 [95% Cl 2,11-2,82]) and Pancreas cancer (2,27 [95% Cl 1,95-2,66]) were higher for DM patients. Regarding sex-specific cancers, the risk of Uterine body cancer was higher for diabetic women  (1,52 [95% Cl 1,17-1,99]), while in men DM seems to have a protective effect, for example in Prostate cancer (0,86 [95% Cl 0,79-0,95]).  CONCLUSIONS: Patients with DM may be at increased risk of total, site-specific and sex-specific cancer.