Rationale: Cardiovascular complications in type 2 diabetes are the leading cause of morbidity and mortality associated with the disease. Endothelial dysfunction is regarded as an important factor in these vascular complications.

The introduction of glucagon-like peptide-1 (GLP-1) analogues and dipeptidyl peptidase IV (DPP-IV) inhibitors for the treatment of type 2 diabetes is of special interest because of possible influences on endothelial function. Numerous reports have shown that GLP-1 improves endothelial function.

Objective: To determine whether a four week treatment with vildagliptin compared to acarbose improves endothelial dysfunction in patients with type 2 diabetes mellitus.

Inclusion Criteria:

• Type 2 diabetes
• Age 35-75 years
• Treatment with metformin monotherapy or metformin combination therapy
• HbA1c <8.0%

Exclusion Criteria:

• Renal disease defined as creatinine level > 130 umol/l
• Liver disease defined as aspartate aminotransferase or alanine aminotransferase level of more than three times the upper limit of normal range
• Current use of acetylsalicylic acid or vitamine K antagonists
• History of smoking within the past year
• History of or current abuse of drugs or alcohol
• History of heartfailure (NYHA class III or IV)
• Abnormalities on ECG that might interfere with current study protocol
• Pregnancy or breastfeeding
• Inability to understand the nature and extent of the trial and procedures required
• Presence of any medical condition that might interfere with the current study protocol
• Participation in a drug trial within 60 days prior to the first dose