The major cause of premature death in renal transplant recipients is cardiovascular disease. Sitagliptin stimulates insulin secretion and inhibits glucagon release, two central mechanisms in PTDM by interaction with a hormone system (incretins) that just recently it has become possible to modulate by drugs. Sitagliptin therefore is an interesting additional drug for the treatment of posttransplant diabetes mellitus in transplanted patients.

The primary objective of the present study is to investigate the effect of sitagliptin on insulin secretion in renal transplant recipients.

Secondary objectives are to study the effect on insulin sensitivity, fasting blood glucose, endothelial function, CsA/Tac blood concentrations.

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.