Inclusion Criteria Type 2 diabetes ,stable dose of Metformin,HbA1c >= 7%, but < 9% Exclusion Criteria Type 1 diabetes mellitus, Body Mass Index (BMI) >40.0 kg/m2, evidence of unstable cardiovascular diseases, NYHA class I to IV, ALT > 1.5 times UNL, creatinine clearance <60 mL/min