Patients with type 2 diabetes mellitus have higher incidence of coronary artery disease or left ventricular dysfunction, particularly diastolic dysfunction. Coronary artery bypass surgery is known to decrease the mortality rate in diabetes. Further exercise training can improve their cardiorespiratory fitness and the control of risk factors in these patients. However, the extent of improvement and the mechanism, especially the changes in left ventricular function, in diabetes after exercise training have not been fully explored.

Subjects will be assigned to the intervention or control group by randomization. Subjects in the intervention group will receive 60% VO2 max moderate aerobic exercise training, twice per week under supervision and three times per week at home, for 12 weeks. All subjects receive left ventricular function test by echocardiography and impedance cardiography, graded maximal exercise test, and biochemical analyses of sugar and lipid before and after 12 weeks. Their dietary intake and physical activity will be inquired every 4 weeks by questionnaires.