Sitagliptin in Renal Transplant Recipients

Inclusion Criteria: * Renal transplant recipient more than 1 year posttransplant with stable renal function (less than 20% deviation in serum creatinine the last 2 months) and stable prednisolone dose for the last 3 months before inclusion. * Patients in need of (additional) oral anti-diabetic treatment: * New onset diabetes patients with fasting plasma glucose 7-8 mmol/ l, and/or 2-hr plasma glucose 12-18 mmol/l after an oral glucose tolerance test (OGTT) * Patients already on oral hypoglycemic therapy, but with HbA1c 8-11% * 18 years of age. * Male patient, or female patient without childbearing potential (surgically sterilized or postmenopausal) or, if female of childbearing potential, is not lactating, has a negative pregnancy test at screening and is willing to utilize an effective method of contraception throughout the study period and for 90 Days following discontinuation of the Study Drugs. * Signed informed consent. Exclusion Criteria: * Treatment with insulin * Severe liver disease. * Estimated GFR \< 25 ml/min/1.73 m2. * Skin disorders that may influence laser Doppler flowmetry investigations. * Pregnant or nursing mothers.