Influence of Endothelial Function on Central and Peripheral Causes Of Exercise Impairment in Type 2 Diabetes

The investigators have found that persons with type 2 diabetes have an impaired ability to perform exercise even without clinically apparent complications. The reasons for this marked abnormality are unknown but are important as the decreased ability to exercise could contribute to the decreased expenditure of physical activity frequently observed in this population and may potentially constitute an early marker of cardiovascular disease. The investigators wish to evaluate the effects of impaired blood flow regulation on exercise capacity and whether the effects are more important in the heart or in the skeletal muscle tissue during exercise. In addition, the investigators are determining whether correcting these abnormalities by two methods of improving blood flow regulation (acutely infusing Vitamin C or three months of chronic exercise training) leads to improved blood flow regulation, improved heart and skeletal muscle tissue function and hence to better exercise capacity in person with type 2 diabetes. This information will provide a more mechanistic understanding of causes of abnormal exercise responses observed in person with type 2 diabetes as well as whether and to what degree responses are modifiable. Interventions that reverse the exercise defect may facilitate patient adherence to prescribed physical activity programs and potentially decrease cardiovascular mortality in this large segment of the population.