Oral Glucose Tolerance Test (OGTT): After an overnight fast, subjects will be given a oral glucose challenge, wherein plasma glucose concentrations will be measured at baseline, T30min, T60min, T90min, and T120min after 75gm oral glucose load. Individuals with fasting glucose of 100-125 mg/dl and/or a 2-hour glucose of 140-199 mg/dL and less than 200 mg/dL will be eligible for study enrollment. OGTT will be repeated at the end of the study.