Exercise-induced improvement in vasodilatory function accompanies increased insulin sensitivity in obesity and type 2 diabetes mellitus.

Exercise-induced improvement in vasodilatory function accompanies increased insulin sensitivity in obesity and type 2 diabetes mellitus. De Filippis E, Cusi K, Ocampo G, Berria R, Buck S, Consoli A, Mandarino LJ. Center for Metabolic Biology, Arizona State University, 350 East Orange Street, P.O. Box 873704, Tempe, Arizona 85287-3704, USA. OBJECTIVE: The present study was undertaken to determine whether improved vasodilatory function accompanies increased insulin sensitivity in overweight, insulin-resistant subjects (OW) and type 2 diabetic patients (T2DM) who participated in an 8-wk exercise training regimen. DESIGN: Before and after training, subjects had euglycemic clamps to determine insulin sensitivity. Brachial artery catheterization was done on another occasion for measurement of vasodilatory function. A lean, healthy, untrained group was studied as nonexercised controls. RESULTS: Training increased oxygen consumption (VO2) peak [OW, 29 +/- 1 to 37 +/- 4 ml/kg fat-free mass (FFM).min; T2DM, 33 +/- 2 to 43 +/- 3 ml/kg FFM.min; P < 0.05] and improved insulin-stimulated glucose disposal (OW, 6.5 +/- 0.5 to 7.2 +/- 0.4 mg/kg FFM.min; T2DM, 3.8 +/- 0.3 to 4.2 +/- 0.3 mg/kg FFM.min; P < 0.05) in insulin resistance. OW and T2DM, before training, had decreased acetylcholine chloride (ACh)- and sodium nitroprusside-mediated vasodilation and decreased reactive hyperemia compared with lean controls. Training increased the vasodilatory response to ACh [OW (30 microg ACh/min), 12.2 +/- 3.4 to 19 +/- 4.2 ml/100 g.min; T2DM (30 microg ACh/min), 10.1 +/- 1.5 to 14.2 +/- 2.1 ml/100 g.min; P < 0.05] in both groups without affecting nitroprusside response. CONCLUSION: Because vasodilatory dysfunction has been postulated to contribute to insulin resistance, the exercise-induced improvement in vasodilatory function may signify changes in the endothelium that could contribute to the improvement in insulin sensitivity observed after aerobic exercise training.