Abstract 3193: Determinants of Improved Insulin Sensitivity after an Exercise and Weight Loss Program in Overweight Male Coronary Patients
Objective: To evaluate the change in insulin sensitivity and its determinants in non-diabetic overweight (BMI>27) men with stable CHD after participation in an exercise and weight loss program.
Methods: Patients performed 4 months of exercise training according to one of 2 protocols: standard cardiac rehabilitation protocol including 25– 40 minutes of aerobic exercise at 65–70% of peak VO2, 3 times/week (N=29), or walking 45– 60 minutes ≥5 times/week at 50 – 60% of peak VO2 (N=29). Additionally, all subjects attended weekly behavioral weight loss sessions. Body weight, BMI, waist and hip circumferences, fat mass and % body fat (by dual energy X-ray absorptiometry), total abdominal, visceral and mid thigh fat (by CT-scan), peak VO2, fasting insulin level, and physical activity energy expenditure (PAEE) (by doubly labeled water technique) were assessed prior to and after the intervention. A metabolic syndrome score (MS-score) was determined from the 5 criteria of the NCEP ATP Panel III. We used the gold standard technique for the evaluation of insulin sensitivity; the euglycemic hyperinsulinemic clamp (adjusted M-value, expressed in mg of glucose/kg of fat free mass/min).
Results: After the intervention the mean weight loss was 6.4 Kg (p<0.001), and the mean improvement in adjusted M-value was 1.5 mg/kg/min (+ 22 %) (p< 0.001). Univariate determinants of baseline adjusted M-value were weight, fat mass, BMI, waist and hip circumferences, total abdominal and mid thigh fat, peak VO2, fasting insulin level, and the MS-score (all p < 0.05), while in multiple regression analysis (adjusting for all variables, including exercise protocol), the only significant determinants were BMI (p= 0.0004) and MS-score (p=0.0003). After the intervention, univariate determinants of improved adjusted M-value were change or delta (Δ) fat mass, Δ % body fat, Δ weight, Δ BMI, Δ waist and Δ hip circumferences, Δ total abdominal and Δ visceral fat, Δ fasting insulin, and baseline and Δ PAEE (all p <0.05), while the only independent predictor of improved M-value was Δ PAEE (p=0.004).
Conclusions: In overweight CHD patients who participate in an exercise and weight loss program the most powerful determinant of increased insulin sensitivity is the change in physical activity energy expenditure.