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

Abstract

AimThe 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 ResultsSeventy non-diabetic participants with CAD, BMI 28–40kg/m2, 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. ConclusionLED 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.