In this study, the investigators aim to investigate whether saxagliptin modulate endothelial progenitor cells number and flow-mediated dilation in newly diagnosed, treatment-naive type 2 diabetic patients.

Inclusion Criteria:

• newly diagnosed type 2 diabetics (diagnosis were made according to the American Diabetes Association Guideline [19] ), treatment naive, age 30-75, hemoglobin A1c (HbA1c) ≥6.5%, fasting c-peptide >1.0ng/L

Exclusion Criteria:

• pregnancy or lactation, smoker, acute disease or infection, chronic renal disease (estimated glomerular filtration rate <60 mL/min/1.73m2), live enzymes 3 times above the normal range, positive islet autoantibody, fasting c-peptide <1.0ng/L, severe hypertriglyceridemia (triglyceride >5.6mmol/L), cardiovascular events or surgery within 3 months, taking glucocorticoid, history of acute or chronic pancreatitis, pancreatic tumor, severe cardiac or pneumonic disease.