| Outcome Measures: |
Primary: change from baseline in glucose after 12-week treatment, OGTT is performed at week 0 (baseline) and 12 (complete treatment). plasma glucose levels are taken at time 0,30,60,90,120 minutes during OGTT., baseline to 12 weeks|change from baseline in HbA1c after 12-week treatment, plasma level of fasting HbA1c is taken at week 0 and 12 of study before OGTT, baseline to 12 weeks|change from baseline in insulin sensitivity/resistance index after 12-week treatment, OGTT is performed at week 0 (baseline) and 12. Plasma levels of glucose and insulin are taken at time 0,30,60,90,120 min during the OGTT. HOMA-IR, HOMA-IS are used to measure insulin resistance and insulin sensitivity at week 0 and week 12, baseline to 12 weeks | Secondary: change from baseline in beta-cell function after 12-week treatment, OGTT is performed at week 0 (baseline) and 12 (treatment complete). HOMS-beta, insulinogenic index, oral disposition index are used to measure beta-cell funciton at week 0 and 12, baseline to 12 weeks
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