α-Lipoic acid can improve endothelial dysfunction in subjects with impaired fasting glucose

Several studies showed that impairment of endothelium-dependent arterial dilation (EDAD) exists in subjects with impaired fasting glucose (IFG). The crucial mechanism of this endothelial dysfunction remains unclear. We hypothesized that oxidative stress may be partially responsible for the impairment in EDAD in subjects with IFG. Thus, the present study was designed to assess whether the antioxidant α-lipoic acid can improve endothelial dysfunction in subjects with IFG. Sixty subjects with newly diagnosed IFG and 32 healthy individuals with normal glucose tolerance were enrolled. Subjects were randomized into 2 groups: untreated experimental group (n = 30) and α-lipoic acid treatment group (n = 30, α-lipoic acid 600 mg via intravenous infusion once a day for 3 weeks). We measured EDAD at baseline and after 3 weeks of intervention. At baseline, EDADs in α-lipoic acid and untreated experimental groups were 4.03% and 4.14%, respectively, which were significantly lower than that in controls (5.72%) (P < .001). After 3 weeks of intervention, there was a remarkable increase in EDAD (reaching 5.10%; ΔEDAD, 26.5%) (P < .01) and a significant decrease in plasma thiobarbituric acid reactive substances (TBARS) (29.1%) (P < .05) in IFG subjects treated with α-lipoic acid. Endothelium-dependent arterial dilation and TBARS remained unchanged before and after intervention in the untreated experimental group. The absolute changes in EDAD showed a significant negative correlation with the changes in TBARS (r = −0.444, P = .014). Our data showed that IFG subjects have impaired endothelial function and that antioxidant α-lipoic acid can improve endothelial function through a decrease of oxygen-derived free radicals.