Alpha-lipoic acid improves vascular endothelial function in patients with type 2 diabetes: a placebo-controlled randomized trial.

OBJECTIVE: The aim of this study was to investigate the effect of alpha-lipoic acid (ALA) treatment on endothelium-dependent and -independent vasodilatation, assessed by forearm blood flow (FBF), in patients with type 2 diabetes mellitus. RESEARCH DESIGN AND METHODS: A total of 30 subjects with type 2 diabetes were included in this randomized, controlled, double-blinded, parallel group study. FBF responses to intra-arterial acetylcholine (ACh) and glycerol trinitrate (GTN) were measured before and after 21 days of intravenous treatment with 600 mg alpha-lipoic acid or placebo. RESULTS: FBF responses were comparable at baseline. After treatment, FBF reactivity to ACh and GTN was unchanged in subjects receiving placebo. By contrast, ALA treatment increased endothelium-dependent vasodilatation to ACh (P < 0.05) but not to GTN compared with baseline. CONCLUSIONS: Intravenous ALA treatment improves endothelium-dependent vasodilatation in patients with type 2 diabetes, in the absence of effects on forearm vasomotor function. If this salutary action translates into vascular risk reduction remains to be established.