The inclusion of regular physical activity is critical for optimal insulin action and glycemic control in individuals with diabetes. Current research suggests that Type II diabetes mellitus can be prevented and that all types of diabetes can be controlled with physical activity, largely through improvements in muscular sensitivity to insulin. This article discusses diabetes prevention and the acute and chronic benefits of exercise for individuals with diabetes, along with the importance and impact of aerobic, resistance, or combined training upon glycemic control. To undertake physical activity safely, individuals also must learn optimal management of glycemia.