Clinical trials have consistently shown a higher incidence of new-onset diabetes mellitus with tacrolimus than cyclosporine. However, in protocol-driven studies steroid doses are comparable in both treatment arms, while in clinical practice steroid dose used in conjunction with tacrolimus or cyclosporine may differ. This retrospective study analysed renal transplant recipients without pre-existing diabetes receiving tacrolimus (n = 100) or cyclosporine (n = 100) for whom one-year follow-up data were available. Diabetes was defined as use of insulin or oral hypoglycemic agents; fasting glucose >6.9 mmol/L; or non-fasting glucose >11 mmol/L on three consecutive occasions. Tacrolimus-treated patients were significantly older than cyclosporine-treated patients (49 +/- 14 vs. 44 +/- 13 yr, p 60 yr [9/28 (32.1%) vs. 0/14 (0%), p