Metabolic and hormonal effects of tacrolimus (FK506) or cyclosporin immunosuppression following renal transplantation

Twelve renal transplant recipients randomised to receive immunosuppression with either tacrolimus (FK506) or cyclosporin underwent oral glucose tolera nce tests (OGTT) a median of 8 months (range 7-9) after transplantation. Si x healthy subjects acted as controls. Compared with the controls, both tran splant groups had significantly elevated fasting (p < 0.05 for both groups) and postprandial (p < 0.001 for tacrolimus and p < 0.05 for cyclosporin) b lood glucose concentrations. Fasting hyperinsulinaemia was observed in both transplant groups (p < 0.05) relative to the control subjects. Glucose-sti mulated plasma immunoreactive insulin concentrations in the tacrolimus-trea tment group were significantly higher than in the cyclosporin group (p < 0. 05) and the controls (p < 0.001). Postprandial blood alanine concentrations were also significantly elevated in the tacrolimus group compared with bot h the controls (p < 0.001) and cyclosporin-treated patients (p < 0.001). Th e raised insulin concentrations with normal or increased blood glucose conc entrations after renal transplantation suggests that insulin resistance was more marked in patients receiving tacrolimus-based immunosuppression.