The first specific aim is to measure the functional capacity of mitochondria in human skeletal muscle in type 2 DM and in those at apparent risk for type 2 DM (obese, sedentary, non-diabetic adults with the Metabolic Syndrome and/or impaired glucose tolerance). The second specific aim is to examine the morphology of mitochondria in human skeletal muscle in type 2 DM and in those at apparent risk for type 2 DM. The third specific aim is to examine the pathogenesis of mitochondrial damage in type 2 DM and in those at apparent risk for type 2 DM. The fourth specific aim is to assess whether exercise and diet can improve mitochondrial function and morphology in type 2 DM and in those at apparent risk for type 2 DM.