Renal failure in patients who have performed a pancreas transplantation is a hazard for the outcome for these patients. The beneficial effect of pancreas transplantation for renal function is not clear. It is of major importance to early find patients who develops a decrease in renal function and start treatment early and closely monitor these patients in order to avoid further deteriorating renal function. In order to achieve this, there is a need for a easy, fast and sensitive method to evaluate renal function. In this study the investigators plan to use the non-invasive MR to evaluate changes in renal function.