Inclusion Criteria:
* Men and women
* All ethnic groups
* Age 65 and older
* Community-dwelling
* Pre-diabetic based on oral glucose tolerance test with 2 hour values of 140 - 199 mg/dL after an oral glucose load, and no diagnosis of diabetes in the past 12 months
* Subjects must have the following laboratory values: Hematocrit ≥ 33%, aspartate aminotransferase \< 2 X upper limit of normal, alanine aminotransferase \< 2 X upper limit of normal, alkaline phosphatase \< 2 X upper limit of normal, normal urinalysis (no clinically significant white blood cells, red blood cells or bacteria), platelets ≥ 100,000, prothrombin time \< 15 seconds and partial thromboplastin time \< 40 seconds, glomerular filtration rate (GFR) ≥ 45ml/min and urine protein ≤ 100 mg/dL by lab urinalysis.
Exclusion Criteria:
* Characterized as frail, defined as the presence of 3 or more of: 1) weak hand grip strength, 2) slow walking speed, 3) low physical activity, 4) unintentional weight loss of ≥ 10 pounds over the past year, 5) self-reported exhaustion
* Resident of nursing home or long-term care facility
* Subjects with diabetes with range fasting glucose in diabetes range (≥ 126 mg/dL), or 2-hour glucose within diabetes range on OGTT (≥ 200 mg/dL).
* Subjects taking drugs known to affect glucose homeostasis
* Untreated depression or Geriatric Depression Scale (GDS) score on 15-item scale \>7
* Diagnosis of any disabling neurologic disease Parkinson's Disease, Amyotrophic Lateral Sclerosis, multiple sclerosis, cerebrovascular accident with residual deficits (muscle weakness or gait disorder), severe neuropathy, diagnosis of dementia or Mini-mental State Exam (MMSE) score \<24, cognitive impairment due to any reason such that the patient is unable to provide informed consent.
* History of moderate-severe heart disease (New York Heart Classification greater than grade II) or pulmonary disease (dyspnea on exertion upon climbing one flight of stairs or less; abnormal breath sounds on auscultation)
* Poorly controlled hypertension (systolic \>160 mmHg, diastolic \>100 mmHg)
* Peripheral arterial disease (history of claudication)
* Moderate to severe valvular heart disease
* Subjects who have been treated with long term (\>30 days) systemic steroids, anabolic steroids, growth hormone or immunosuppresants within the last 6 months. Males with a medical history of testosterone deficiency who are on a stable dose of testosterone replacement (for ≥ 3 months) are allowed.
* Subjects who have been treated with short term (\<30 days) systemic steroids, anabolic steroids, growth hormone or immunosuppressants within the last 1 month.
* Chronic inflammatory condition, autoimmune disease, or infectious processes (e.g., active tuberculosis, Human Immunodeficiency Virus, rheumatoid arthritis, systemic lupus erythematosus, acute or chronic hepatitis B or C)
* Active tobacco use (within 6 months)
* Illicit drug use
* Active malignancy, non-skin
* Disease or condition likely to cause death within 5 years
* Hypersensitivity to metformin or pioglitazone
* Any disease or condition considered to be exclusionary based on the clinical opinion and discretion of the PI
