Insulin sensitivity improvement with exercise training is mediated by body weight loss in subjects with metabolic syndrome. - GreenMedInfo Summary

AIM: - To determine whether exercise training improves insulin actions through concomitant body weight loss (BWL).

METHODS: - Subjects (aged 55± 8 years) with metabolic syndrome (MetS), prediabetes (fasting blood glucose: 111 ± 2 mg·dL, HbA1c: 5.85± 0.05%) and abdominal obesity (waist circumference: 104 ± 7.9 cm) were randomly allocated to either a group performing aerobic interval training (EXER; n = 76) or a sedentary group receiving lifestyle counselling (CONT; n = 20) for 16 weeks. Results - At baseline, insulin sensitivity (according to HOMA2 and intravenous glucose tolerance test; CS), body composition and VOwere similar between the groups. After the intervention, both groups had similar BWL (1-2%), but only the EXER group showed decreased [mean (95% CI)] trunk fat mass [from 18.2 (17.4-18.9) to 17.3 kg (16.6-17.9); P<0.001] and HOMA2 scores [from 1.6 (1.5-1.7) to 1.4 (1.3-1.5); P = 0.001], and increased VO[from 2.07 (1.92-2.21) to 2.28 (2.11-2.45) LO·min; P<0.001]. However, CSdid not improve in any group. Within-group subdivision by BWL (≤ 0%, 0-3%, ≥ 3%) revealed higher CSin those with BWL≥ 3% in both groups. Trunk fat mass reductions were closely associated with CSand HOMA-IR improvement (r = -0.452-0.349; P<0.001).

CONCLUSION: - In obese MetS subjects with prediabetes, 3% BWL is required for consistent improvement in insulin sensitivity. Thus, exercise-training programmes should be combined with calorie restriction to achieve BWL levels that prevent the development of diabetes.