The purpose of this study is to determine the effects of metformin on cardiovascular risk factors in postmenopausal women with metabolic syndrome.

Inclusion Criteria:

• Postmenopausal women aged 45-60 years with metabolic syndrome according to The American Heart Association and The National Heart, Lung, and Blood Institute

Exclusion Criteria:

• Previous cardiovascular diseases
• Contraindicated to metformin: serum creatinine >1.4 mg/dL, liver disease, alcoholism, congestive heart failure, chronic hypoxic lung disease, prior history of lactic acidosis
• Previous administration of metformin, other hypoglycemic drugs, lipid-lowering drugs, sex steroids, antiplatelet drugs within 3 months before enrollment
• Fasting blood sugar ≥ 200 mg/dL or HbA1c >8%
• Serum triglyceride ≥500 mg/dL
• Abnormal EKG