Insulin Resistance and Testosterone in Women

Inclusion Criteria: * Postmenopausal women aged 50-79 years with absence of menses for 12 months; for women 50-54 years, Follicle stimulating hormone\>30 U/mL to confirm postmenopausal status * At least one intact ovary * Free testosterone and fasting insulin levels within required study parameters * Willing to comply with all study-related procedures * Capable of giving informed consent Exclusion Criteria: * History of cancer requiring treatment within the past 5 years (exceptions may be made by investigator) * Hospitalization for treatment of vascular disease in the past 6 months * Uncontrolled hypertension * Hospitalization for chronic obstructive pulmonary disease or asthma in the past 3 months * Use of continuous oxygen at home * Surgery in the last 30 days * Positive for HIV * Abnormal blood tests (hemoglobin, fasting triglycerides, fasting glucose, creatinine, liver function) * History of diabetes mellitus or use of any anti-hyperglycemic medication in the past 3 months * Disease associated with disordered glucose metabolism (Cushing's disease, acromegaly, pheochromocytoma not surgically cured, chronic pancreatitis) * History of chronic renal insufficiency * Intravenous (IV) contrast studies with iodinated materials planned for the 12 week intervention period that cannot be postponed according to the participant's primary care provider * Acute or chronic metabolic acidosis * History of liver disease * Congestive heart failure * History of androgen-secreting tumors * Hormone replacement therapy or antiandrogen use in past 6 months * Use of dehydroepiandosterone (DHEA) or other androgen-containing products in past 6 months * Corticosteroid use, other than topical, ophthalmic, intraarticular, and inhaled preparations, in past 3 months * Undiagnosed current vaginal bleeding * Excessive alcohol intake, either acute or chronic; current illicit substance abuse * Participation in an investigational drug study within 6 weeks prior to screening visit * Serious or unstable medical or psychological conditions that, in the opinion of the investigator, would compromise the patient's safety or successful participation in the study