To investigate whether single administration of sitaglitpin can restore acute endothelial dysfunction and ameliorate impaired increase of the number of endothelial progenitor cells (EPCs) after oral glucose loading in patients with T2DM.

To compare the effect of sitagliptin and glimepiride on endothelial function evaluated by flow-mediated vasodilatation (FMD) and the number of circulating EPCs in patients with T2DM.

Acute and chronic improvement of endothelial function is expected through the pleiotropic effect of DPP-4 inhibitors. A randomized, prospective, open-labeled, parallel design. The duration of treatments with sitagliptin or glimepiride is 12 weeks. The number of study centers is a single (Dokkyo Medical University Hospital). Participants will be randomized into the two treatment groups; (a) 50mg sitagliptin (N=15) and (b) 1mg glimepiride (N=15).

Anti-Hyperglycemic effect is expected to be similar according to our study

Inclusion Criteria:

• Provision of informed consent before any study specific procedures
• Type II diabetes who have inadequate glycaemic control (6.5%≦HbA1c<9.0%)
• Age from 20 to 80 years old
• No history of using any antihyperglycemic drugs
• No history of cardiovascular complications
• No treatment or treatment with stable doses of lipid-lowering, antihypertensive, and antiplatelet agents for at least 3 months prior to randomization
• 4.5 % ≤ fasting FMD at baseline < 8.0 %

Exclusion Criteria:

• ・Type I diabetes

  • Pregnancy
  • Liver disease (hepatic enzymes more than three times the upper limit of normal ranges)
  • Impairared kidney function (serum crearinine greater than 1.3 mg/dl in men, 1.2 mg/dl in women)
  • Cigarette smokers
  • Contraindications to glimepiride and sitagliptin
  • Active proliferative diabetic retinopathy