Regular physical exercise is important in the prevention and treatment of type 2 diabetes. A single exercise session can influence systemic glucose homeostasis by both increasing glucose uptake into the contracting muscles during exercise, and increasing the sensitivity of muscle glucose uptake to insulin for a prolonged period after the cessation of exercise. The underlying cellular mechanisms responsible for these important effects of a single exercise session are not well understood. Exercise training can also result in changes in skeletal muscle insulin sensitivity, mediated partly by the acute effects of the individual exercise bouts and also by numerous chronic adaptations to the muscle, including increased expression of GLUT4.