Effects of Exercise Training on Left Ventricular Function in Type 2 Diabetic Patients Post Coronary Artery Bypass Graft

• Exercise capacity [ Time Frame: Three months after the start of the intervention ] [ Designated as safety issue: No ]
  Exercise capacity was assessed by peak oxygen uptake (VO2peak)via exercise testing. VO2peak was measured by a metabolic measurement system (Vmax229 Metabolic Measurement System, Sensor Medics, Anaheim, CA).
  
  
• Diastolic heart function [ Time Frame: Three months after the start of the intervention ] [ Designated as safety issue: No ]
  Echocardiographic examination including color B mode TDI with a commercially available 2.5- to 3.75-MHz phased array transducer (Philips, SONOS 5500, Andover, MA)was used to evaluate diastolic function.
  
  

• Endothelial function [ Time Frame: Three months after the start of the intervention ] [ Designated as safety issue: No ]
  Examined by flow-mediated vasodilation
  
  
• Hemodynamics [ Time Frame: Three times after the start of the intervention ] [ Designated as safety issue: No ]
  Heart rate (HR) and stroke volume (SV) were collected at rest, during the exercise test, and during the recovery phase by a noninvasive bioimpedance cardiograph device (PhysioFlow PF-05, Manatec Biomedical, Paris, France). Cardiac output (CO) and arteriovenous oxygen difference ((a-v)O2 difference) were then determined by the following equations: CO=HR*SV and (a-v)O2 difference=VO2/SV*HR
  
  
• Blood test [ Time Frame: Three months after the start of the intervention ] [ Designated as safety issue: No ]
  Including fasting glucose, HbA1c, total cholesterol (TC), high-density liporpotein (HDL-c) and triglyceride (TG).
  
  

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.