OBJECTIVE Post-transplant diabetes mellitus (PTDM) is a common and potentially serious complication after solid organ transplantation. There are only a few data, however, about the incidence of DM in patients undergoing lung transplantation. METHODS The medical records of 119 consecutive patients who underwent lung transplantation from 1998 to September 2004 were reviewed. Patients were divided in three groups according to their diabetes status, including pre-transplant DM, the PTDM group and those without DM. Patient records and all laboratory data were reviewed and the clinical course of diabetes was monitored. All recipients were treated with tacrolimus based regimen. RESULTS Mean follow-up for all patients was 25+/-10. Twenty-three patients had DM in the pre-lung transplantation (LTX) DM group. PTDM developed in 34 of the remaining 96 patients (35.4%) with an incidence of 20%, 23% after 6 months and 12 months post-transplant. No significant difference was noted between 12 and 24 months post-LTX. The patients who developed DM were older (57+/-15 vs 53+/-13 years, p=0.009), had increased BMI (26+/-5 vs 24+/-4, p=0.0001), shorter time from diagnosis to LTX (21+/-13 vs 28+/-18 months, p=0.007) more cytomegalovirus infection and more acute rejection and hyperglycemia in the first month after LTX. Four patients died in the PTDM group compared to nine patients in the no-DM group (12% vs 14%; p=0.72). CONCLUSIONS Post-transplant diabetes is a common complication in lung transplant patients receiving tacrolimus-based immunosuppression. The risk for developing PTDM is greatest among older recipients, those obese, and among recipients with more rejections episodes.