The aim of this pilot-study is to investigate the effect of Vildagliptin in comparison to glimepiride on beta cell function and the cardiovascular risk profile in patients previously treated with Metformin monotherapy.

Inclusion Criteria:

• Diabetes mellitus type 2

• HbA1c > 6.5%* ≤ 9.5%

  * NOTE: Patients with cardiovascular preconditions (Coronary Heart Disease or Myocard Infarction) require an HbA1c > 7.0% ≤ 9.5%

• Treatment with Metformin at maximal or maximal tolerated dosage, stable for at least 3 months with indication for treatment with an additional medication as judged by the investigator

• Age 30 - 80 years

• Patient consents that his/her family physician will be informed of trial participation

Exclusion Criteria:

• Pre-treatment with insulin, peroxisome proliferator activated receptor (PPAR) gamma agonists or other oral antidiabetic treatments (except Metformin) within the last three months
• History of type-1-diabetes
• Fasting blood glucose >240mg/dl
• Uncontrolled hypertension (systolic blood pressure >160 and/or diastolic blood pressure >90)
• Anamnestic history of acute infections
• Anamnestic history of epilepsy
• Anamnestic history of hypersensitivity to the study drugs or to drugs with similar chemical structures
• History of severe or multiple allergies
• Hereditary galactose intolerance, lapp-lactase defect or glucose-galactose mal-absorption
• Treatment with any other investigational drug within 3 months before trial entry
• Pregnant or lactating women
• Sexually active woman of childbearing age not practicing a highly effective method of birth control as defined as those which result in a low failure rate (i.e. less than 1% per year) when used consistently and correctly such as implants, injectables, combined oral contraceptives, hormonal intrauterine devices, sexual abstinence or vasectomized partner
• Progressive fatal disease
• History of drug or alcohol abuse in the past 2 years
• State after kidney transplantation
• Serum potassium > 5.5 mmol/L
• Acute myocardial infarction, open heart surgery or cerebral event (stroke/transient ischemic attack) within the previous 6 months
• Any elective surgery during study participation
• Have had more than one unexplained episode of severe hypoglycemia (defined as requiring assistance of another person due to disabling hypoglycemia) within 6 months prior to screening visit
• History of pancreatitis
• Anamnestic history of dehydration, diabetic precoma or diabetic ketoacidosis
• Acute or scheduled investigation with iodine containing radiopaque material
• Uncontrolled unstable angina pectoris
• Anamnestic history of pericarditis, myocarditis, endocarditis, hemodynamic relevant aortic stenosis, aortic aneurysm or heart insufficiency NYHA III or IV
• Anamnestic recent pulmonary embolism
• History of significant cardiovascular, respiratory, gastrointestinal, hepatic (ALAT and/or ASAT > 3 times the normal reference range), renal (GFR < 60 ml), neurological, psychiatric and/or hematological disease as judged by the investigator
• Lack of compliance or other similar reason that, according to investigator, precludes satisfactory participation in the study