The rising incidence of diabetes and the associated metabolic diseases including obesity, cardiovascular disease and hypertension have led to investigation of a number of drugs to treat these diseases. However, lifestyle interventions including diet and exercise remain the first line of defense. The benefits of exercise are typically presented in terms of weight loss, improved body composition and reduced fat mass, but exercise can have many other beneficial effects. Acute effects of exercise include major changes in blood flow through active muscle, an active hyperemia that increases the delivery of oxygen to the working muscle fibers. Longer term exercise training can affect the vasculature, improving endothelial health and possibly basal metabolic rates. Further, insulin sensitivity is improved both acutely after a single bout of exercise and shows chronic effects with exercise training, effectively reducing diabetes risk. Exercisemediated improvements in endothelial function may also reduce complications associated with both diabetes and other metabolic disease. Thus, while drugs to improve microvascular function in diabetes continue to be investigated, exercise can also provide many similar benefits on endothelial function and should remain the first prescription when treating insulin resistance and diabetes. This review will investigate the effects of exercise on the blood vessel and the potential benefits of exercise on cardiovascular disease and diabetes. KeywordsExercise; Diabetes; Insulin; Muscle; Vasculature; Blood vesselsThe prevalence of diabetes has been increasing steadily in the United States and in many parts of the world. In 2010, 25.8 million individuals in the United States were diagnosed with diabetes, a figure almost double that of ten years previously [1]. Diabetes frequently occurs with other diseases, including dislipidemia, hypertension, cardiovascular disease and obesity. Exercise is also associated with significant improvements in other aspects of disease, such as the reduction of complications, associated metabolic diseases, and other risk factors [9]. The metabolic syndrome, typified by high blood pressure, high triglyceride levels, low HDLcholesterol levels, high fasting glucose, and central obesity, is recognized to predispose individuals to the development of diabetes and atherosclerosis. Interestingly, most of the criteria of the metabolic syndrome pertain to blood measurements, and can therefore affect blood vessels. Further, many of the complications of diabetes, including retinopathy, kidney disease and peripheral neuropathy, also have a vascular basis. In their review, Joyner and Green note that exercise is much more protective against cardiovascular disease than would be expected based on changes in traditional risk factors, including BMI, blood lipids and blood pressure [10]. They suggest a vicious cycle between autonomic dysfunction and endothelial dysfunction leading to cardiovascular disease, which can be prevented by exercise [10]. Here, the role of the endothe...