Exercise Training in Type 2 Diabetes and Hypertension

Type 2 diabetes is associated with damage, dysfunction, and failure of various organs. The coexistence of diabetes and hypertension is particularly damaging to cardiac and peripheral vascular structure and function. These diseases, either alone or combined, result in increased left ventricular mass and wall thickness, left ventricular diastolic dysfunction, impaired endothelial vasodilator function, and increased vascular stiffness. Although several health organizations endorse exercise training as a therapeutic modality for type 2 diabetes, most studies of exercise and diabetes have focused on glycemic control but not on cardiovascular health. Although exercise lowers blood pressure in persons without diabetes, there are profound gaps in knowledge about the effects of exercise training on blood pressure and cardiovascular health in persons with type 2 diabetes. The primary specific aim of this study is to determine if exercise training reduces blood pressure in persons who have both type 2 diabetes and high normal blood pressure or mild hypertension prehypertension or Stage 1 (mild) hypertension. Subjects will be randomized to 6-months of exercise training, consistent with established guidelines for diabetes and for hypertension, or to a usual care control group. The second specific aim is to identify the effects of exercise training on parameters of cardiac and peripheral vascular structure and function related to cardiovascular disease in diabetes and hypertension. We will assess left ventricular mass, left ventricular diastolic function, endothelial vasodilator function, and vascular stiffness using high-resolution ultrasound, Doppler echocardiography, and magnetic resonance imaging. We will also examine interleukin-6 and high-resolution C-reactive protein as novel risk factors for cardiovascular disease and diabetes to determine the effects of exercise training on the inflammatory process. Because exercise training improves fitness and may improve body composition and regional fat distribution, the associations of change in these parameters with change in blood pressure and cardiac and peripheral vascular structure and function will be analyzed. An equal number of men and women will be enrolled, and a third specific aim of the study is to examine gender differences in response to exercise training. This study will expand the scientific knowledge that defines exercise guidelines and will provide new insight into the mechanisms by which exercise reduces blood pressure and improves cardiovascular health in persons with type 2 diabetes and hypertension.