A randomized trial comparing the effect of weight loss and exercise training on insulin sensitivity and glucose metabolism in coronary artery disease

AIM: The majority of patients with coronary artery disease (CAD) exhibit abnormal glucose metabolism, which is associated with mortality even at non-diabetic glucose levels. This trial aims to compare the effects of a considerable weight loss and exercise with limited weight loss on glucose metabolism in prediabetic, CAD patients.

METHODS AND RESULTS: Seventy non-diabetic participants with CAD, BMI 28-40kg/m(2), age 45-75 years were randomized to 12weeks' aerobic interval training (AIT) at 90% peak heart rate three times weekly or a low energy diet (LED, 800-1000kcal/day) for 8-10 weeks followed by 2-4 weeks' weight maintenance diet. Glucose tolerance, insulin action, β-cell function and suppression of lipolysis were assessed using a 3-h oral glucose tolerance test. ISI-composite and ISI-HOMA (=1/HOMA-IR) were calculated as surrogate measures of whole-body and hepatic insulin sensitivity, respectively. Magnetic resonance imaging estimated abdominal adipose tissue. Twenty-six (74%) AIT and 29 (83%) LED participants completed intervention per protocol. LED increased ISI-composite by 55% and ISI-HOMA by 70% (p<0.01) while AIT did not change insulin sensitivity (p>0.7) revealing a significant difference between the groups (p<0.05). No concurrent significant changes in lipolysis, β-cell responsiveness or insulin clearance were seen. Changes in ISI-HOMA and ISI-composite were associated with reduced visceral abdominal fat, waist circumference and body weight. Intention-to-treat analyses (n=64) yielded similar results.

CONCLUSION: LED is superior to AIT in improving insulin sensitivity in prediabetic CAD patients. Changes in insulin sensitivity are associated with decreased visceral abdominal fat, waist circumference and body weight.