DPP-4 Inhibition and TZD for DM Prevention

Inclusion Criteria: * Impaired glucose tolerance (IGT) by oral glucose tolerance test Exclusion Criteria: * History of diabetes mellitus * History of congestive heart failure * History of coronary artery disease or other macrovascular disease (stroke, peripheral vascular disease) * History of liver disease (ALT or AST \>2.5 times the upper limit of normals) * History of renal disease (serum creatinine \>1.5 mg/dl) * History of severe osteoporosis (frequent fractures, failure on osteoporosis treatment) * Current treatment with glucocorticoids * History of immune disorder, including HIV * Women of child-bearing age who are pregnant, desire to become pregnant, are breastfeeding, or who refuse to take the recommended birth control measures