Abstract

BACKGROUND
Exercise offers protection against atherosclerosis and insulin resistance. We evaluated the benefits of exercise at different levels of intensity for ameliorating inflammation, endothelial dysfunction, and insulin resistance in a sample of type 2 diabetic subjects. METHODS: Fifty-nine overweight women with type 2 diabetes were randomly assigned to control (CG, N = 18), moderate-intensity exercise (MEG, N = 17), and vigorous-intensity exercise (VEG, N = 14) groups. Patients in the two experimental groups completed a 12-week exercise program, with their exercise activities monitored by accelerometers. We assessed the patients' body weights, total abdominal fat (TF), subcutaneous fat (SF) and visceral fat (VF) via computed tomography, measurements of plasma levels of hs-C-reactive protein (hs-CRP) and interleukin-6 (IL-6), assessment of endothelial function by brachial artery flow-mediated dilation (FMD), and evaluation of insulin sensitivity by insulin tolerance tests, at baseline, at the end of the 12-week interventions, and one year after initiation of the study. RESULTS: At baseline, the average age of all subjects was 54 +/- 7 years, and average body mass index (BMI) was 26.9 +/- 2.5 kg/m2. During the intervention, patients in the MEG and VEG groups expended comparable amounts of activity-related calories (488.6 +/- 111.9 kcal/day, 518.8 +/- 104.1 kcal/day, respectively). Although BMI, TF, and SF decreased similarly in the MEG and VEG groups (deltaBMI: -1.1 +/- 0.7, -0.8 +/- 0.5, deltaTF: -4,647 +/- 3,613 mm2, -2,577 +/- 2,872 mm2, deltaSF: -2,057 +/- 2,021 mm2, -1,141 +/- 1,825 mm2, respectively), compared to control (P<0.01), hs-CRP, IL-6, and FMD remained constant in both exercise groups even after completion of the 12-week exercise intervention. Insulin sensitivity improved only in patients subjected to vigorous exercise (VEG). Visceral fat loss was observed only in patients subjected to moderate exercise (MEG). At one-year follow up, these values had all returned to baseline. CONCLUSION: Exercise vigorous enough to result in significant weight and fat reduction did not ameliorate inflammation and endothelial dysfunction as measured at the end of a 12-week exercise intervention, nor did it result in sustained improvements in insulin sensitivity in type 2 diabetic subjects.

• Keywords: Exercise;Insulin resistance;Type 2 diabetes mellitus