Exercise training improves vascular endothelial function in patients with type 1 diabetes

OBJECTIVE - Impaired endothelial function of resistance and conduit arteries can be detected in patients with type 1 diabetes. We studied whether a persistent improvement of endothelial function can be achieved by regular physical training. RESEARCH DESIGN AND METHODS - The study included 26 patients with type 1 diabetes of 20 ± 10 years' duration and no overt angiopathy; 18 patients (42 ± 10 years old) participated in a bicycle exercise training program, and 8 patients with type 1 diabetes (33 ± 11 years old) served as control subjects. Vascular function of conduit arteries was assessed by flow-mediated and endothelium-independent dilation of the brachial artery and of resistance vessels by the response of ocular fundus pulsation amplitudes to intravenous N^G-monomethyl-L-arginine (L-NMMA) at baseline, after 2 and 4 months of training, and 8 months after cessation of regular exercise. RESULTS - Training increased peak oxygen uptake (VO_2max) by 13% after 2 months and by 27% after 4 months (P = 0.04). Flow-mediated dilation (FMD) of the brachial artery increased from 6.5 ± 1.1 to 9.8 ± 1.1% (P = 0.04) by training. L-NMMA administration decreased fundus pulsation amplitude (FPA) by 9.1 ± 0.9% before training and by 13.4 ± 1.5% after 4 months of training (P = 0.02). VO_2max, FMD, and FPA were unchanged in the control group. Vascular effects from training were abrogated 8 months after cessation of exercise. CONCLUSIONS - Our study demonstrates that aerobic exercise training can improve endothelial function in different vascular beds in patients with long-standing type 1 diabetes, who are at considerable risk for diabetic angiopathy. However, the beneficial effect on vascular function is not maintained in the absence of exercise.