Effects of l-arginine supplementation on blood flow, oxidative stress status and exercise responses in young adults with uncomplicated type I diabetes
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- Fayh, A.P.T., Krause, M., Rodrigues-Krause, J. et al. Eur J Nutr (2013) 52: 975. doi:10.1007/s00394-012-0404-7
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Background and aims
Vascular disease is the principal cause of death and disability in patients with diabetes, and endothelial dysfunction seems to be the major cause in its pathogenesis. Since l-arginine levels are diminished in conditions such as type 1 and type 2 diabetes, in this work we aimed to verify the effects of l-arginine supplementation (7 g/day) over the endothelial function and oxidative stress markers in young male adults with uncomplicated type 1 diabetes. We also investigated the influences of l-arginine administration on vascular/oxidative stress responses to an acute bout of exercise.
Ten young adult male subjects with uncomplicated type 1 diabetes and twenty matched controls volunteered for this study. We analysed the influence of l-arginine supplementation (7 g/day during 1 week) over lower limb blood flow (using a venous occlusion plethysmography technique), oxidative stress marker (TBARS, Carbonyls), anti-oxidant parameters (uric acid and TRAP) and total tNOx in rest conditions and after a single bout of submaximal exercise (VO2 at 10 % below the second ventilatory threshold). Data described as mean ± standard error (SE). Alpha level was P < 0.05.
Glycaemic control parameters were altered in type 1 diabetic subjects, such as HbA1c (5.5 ± 0.03 vs. 8.3 ± 0.4 %) and fasted glycaemia (94.8 ± 1.4 vs. 183 ± 19 mg/dL). Oxidative stress/damage markers (carbonyls and TBARS) were increased in the diabetic group, while uric acid was decreased. Rest lower limb blood flow was lower in type 1 diabetic subjects than in healthy controls (3.53 ± 0.35 vs. 2.66 ± 0.3 ml 100 ml−¹ min−¹). l-Arginine supplementation completely recovered basal blood flow to normal levels in type 1 diabetics’ subjects (2.66 ± 0.3 to 4.74 ± 0.86 ml 100 ml−¹ min−¹) but did not interfere in any parameter of redox state or exercise.
Our findings highlight the importance of l-arginine for the improvement of vascular function in subjects with diabetes, indicating that l-arginine supplementation could be an essential tool for the treatment for the disease complications, at least in non-complicated diabetes. However, based on our data, it is not possible to draw conclusions regarding the mechanisms by which l-arginine therapy is inducing improvements on cardiovascular function, but this important issue requires further investigations.