All clinical and laboratory examinations to evaluate the investigational drug's efficacy, will be performed at baseline, Week 8th and Week 12th (end) of study treatment. Blood glucose level (both FPG and 2h-PG) will be performed at baseline and at interval of 4 weeks over the 12 weeks of study treatment. Safety examinations will be performed at baseline and at the end of study. Occurrence of adverse event will be observed during the study.