One of the main side-effects of tacrolimus in solid organ transplanted patients is post transplant diabetes mellitus (PTDM). It is not known if different pharmacokinetic properties influence the risk of developing PTDM. It is possible that it either is high peak concentrations of high overall systemic exponation that is responsible for the effect on insulin secretion. With the new slow-release formulation of tacrolimus (Advagraf) a different pharmacokinetic profile is introduced to patients and it is of interest to investigate if this affects insulin secretion and insulin sensitivity of patients.