Tacrolimus (TRL) increases the incidence of new-onset diabetes mellitus after transplantation (NODAT). Little is known about whether conversion from TRL to cyclosporine A (CsA) improves glucose metabolism in patients with NODAT. We retrospectively analysed glucose metabolism parameters in 54 TRL-treated renal transplant patients who developed NODAT. Thirty-four were converted to CsA whereas 20 patients continued TRL. After conversion, fasting plasma glucose decreased from 146 +/- 64 to 104 +/- 20 mg/dl (P < 0.0001) and HbA1c levels decreased from 6.8 +/- 0.8% to 6.0 +/- 0.6% (P < 0.0001) after 1 year of follow-up. The remission rate of NODAT reached 42% (95% confidence interval 24-59%) 1 year after conversion versus 0% in the control group (P = 0.001). Blood pressure and lipid levels were stable after conversion although the use of statins significantly increased (P < 0.01). The conversion was safe in terms of graft function and acute rejection episodes. The 1-year patient survival and graft survival rate were 100%. In conclusion, our results suggest a significant improvement of glucose metabolism after conversion to CsA in renal transplant patients with NODAT.