The discovery of the role of endothelial progenitor cells (EPCs) and their involvement in the cardiovascular complications of type 2 diabetes (T2DM) would quickly have a significant impact on the millions of Americans who have T2DM. This project is designed to 1) determine the mechanisms underlying EPC dysfunction in older, sedentary adults with T2DM compared those with normal glucose metabolism and impaired glucose metabolism, and 2) determine if aerobic exercise training is an efficacious therapy for EPC dysfunction in T2DM, and whether improvement in EPC number and function translates to improved endothelial function, increased capillarization, and improved glucose metabolism in T2DM.