The purpose of this study was to investigate the incidence and risk factors for the development of diabetes mellitus after kidney transplantation (PTDM). A total of 1783 nondiabetic renal allograft recipients transplanted from January 2000 to December 2002 were included. Diabetes was diagnosed following American Diabetes Association criteria. While 1276 patients were treated with tacrolimus (Tac), mycophenolate mofetil (MMF), and steroids, 507 patients received cyclosporine-ME (CsA), MMF, and steroids. PTDM incidence at 6, 12, and 24 months was 14.2%, 12.8%, and 13.3%, respectively. Cumulative incidence during the follow-up was 21.6%. Only 121 of the diabetic patients (47.6%) at 6 months remained diabetic at 24 months. Furthermore, 60 patients of 116 patients on insulin at 6 months (51.7%) remained on treatment at 24 months. The cumulative incidence of PTDM was similar in the two immunosuppressive treatments (19.7% on CsA-MMF vs 22.3% on Tac-MMF; P = NS). However, at 24 months, 14 of 50 diabetic patients on CsA-MMF (28%) and 74 of 161 patients on Tac-MMF (45.9%) were on insulin treatment (P < .05). By Cox regression analysis, age older than 60 years (RR 1.61; 95%CI 1.28-2.04; P < .001), body mass index (BMI) > 30 kg/m2 at transplantation (RR 1.66; 95%CI 1.27-2.16; P < .001), and immunosuppression with Tac (RR 1.30; 95%CI 1.02-1-66; P = .033) were associated with PTDM. In conclusions, the incidence of PTDM at 24 months in immunosuppressive protocols including MMF is about 22%, and it is associated with older age, increased BMI, and immnunosuppression with Tac.