New-onset diabetes mellitus (NODM)-a common complication of kidney transplantation-is associated with increases in graft loss, morbidity and mortality. This is a purely observational study of 527 patients taking a calcineurin inhibitor (CNI), based on data collected at a single routine visit 6-24 months after kidney transplantation. Diabetes was defined according to ADA/WHO guidelines. The mean age of the patients was 47.2 years and 61.1% were men; 49.5% were receiving cyclosporine microemulsion (CsA-ME) and 50.5% tacrolimus (Tac). NODM developed in 7.0% after a median interval of 1.6 months. In CsA-ME-treated patients, the unadjusted cumulative risks of NODM were 5.5% and 8.4% at 1- and 2-year post-transplantation, while in Tac-treated patients, the risks were respectively 17.4% and 21%. Four independent risk factors (RFs) were identified by multivariate analysis: maximum lifetime body mass index>25 [odds ratio (OR)=5.1], pre-transplantation impaired fasting glucose (OR=4.7), hepatitis C status (OR=4.7) and Tac vs CsA-ME treatment (OR=3.0). NODM is associated with certain RFs present prior to kidney transplantation, and with treatment with Tac as opposed to CsA-ME.