There is a well established relationship between physical activity, metabolism, diabetes, and cardiovascular risk. In fact, numerous prospective epidemiological studies demonstrate an inverse correlation between physical activity and mortality, both cardiovascular and all cause mortality. This association is plausible when considered in the context of the impact of physical activity upon metabolic parameters that modulate cardiovascular risk such as blood pressure, dyslipidemia, inflammatory markers, and carbohydrate tolerance. Exercise is also pivotal for weight maintenance and prevention of obesity, a leading cause of new onset diabetes, which in turn contributes significantly to cardiovascular disease burden and mortality, as well as to noncardiac and all cause mortality. Prospective studies demonstrate the ability of diet and exercise to prevent progression from impaired glucose tolerance to diabetes. Despite the salutary effects of exercise on diabetes and cardiovascular risk, recent literature indicates that people with diabetes do not exercise as much as those without. This failure to exercise is likely behavioral and functional. Our recent work demonstrates that there are defects in both maximal and submaximal exercise function in persons with type 2 diabetes mellitus. In this chapter, we will review the cardiovascular and metabolic impacts of exercise, the relationship of exercise to diabetes prevention, and work from our lab examining the impact of diabetes on exercise capacity with some insights into the general mechanisms likely to be involved. The later chapters in this section will outline the impact of exercise on body composition and on cardiac, skeletal muscle, and endothelial function in additional detail .