Exercise is medicine-the importance of physical activity, exercise training, cardiorespiratory fitness, and obesity in the prevention and treatment of type 2 diabetes

Type 2 diabetes has reached epidemic proportions worldwide and is associated with increased risk of cardiovascular diseases and premature mortality. Diet and physical activity (PA)-based lifestyle interventions have been shown to prevent progression to type 2 diabetes in patients at high risk. Regular PA substantially reduces the risk of type 2 diabetes and a high level of PA is associated with a substantial reduction in type 2 diabetes risk. In addition, there is strong evidence suggesting a steep inverse relationship between both PA and cardiorespiratory fitness (CRF) and mortality in patients with type 2 diabetes. Of particular concern is the dramatic, steep increase in mortality among patients with low CRF. An important point is that obese individuals who are at least moderately fit have a lower mortality risk than those who are normal weight but unfit. A large body of evidence demonstrates that exercise improves glycaemic control in type 2 diabetes; the greatest improvements are achieved with combined aerobic and resistance training. A primary goal of public health strategies is to promote PA and move patients out of the least fit, highrisk cohort by increasing PA among the least active. Any plan to deal with the global epidemic of type 2 diabetes must give major attention to low PA and how this can be reversed in the general population.