This randomized, double-blind, placebo-controlled, multicenter study enrolled 236 patients with symptomatic polyneuropathy. Subjects were treated with 600 mg tid alpha lipoic acid (n=117) or placebo (n=119) for 12 weeks. This study found that 73.27% of the patients with symptomatic polyneuropathy improved after treatment with alpha lipoic acid, compared to 18.27% receiving placebo. The most common adverse event was a burning sensation from throat to stomach (11.8%). The investigators concluded that 600 mg tid alpha lipoic acid is safe and can benefit patients with diabetic polyneuropathy.
A randomized, controlled trial studied the effects of alpha lipoic acid treatment on endothelial-dependent and -independent vasodilation in 30 patients with type 2 diabetes. Treatment with alpha lipoic acid was found to significantly increase endothelium-dependent vasodilation. Treatment was found to be well-tolerated, with no adverse effects observed. The investigators concluded that intravenous alpha lipoic acid treatment improves endothelium vasodilation in patients with type 2 diabetes in the absence of effects on vasomotor function.
A meta-analysis of clinical trials of alpha-lipoic acid and symptomatic polyneuropathy. Four trials met the stringent inclusion criteria (randomized, double-blind, placebo, using 600 mg i.v. per day for three weeks, except for weekends, in diabetic patients with positive sensory symptoms of polyneuropathy scored by the Total System Score in the feet on a daily basis). The analysis included 1258 patients following an intention-to-treat principle. Improvement was first noted after eight days of treatment. After three weeks, responder rates for patients receiving alpha-lipoic acid was 53% versus 37% for placebo. The difference was statistically significant. Rates of adverse events did not differ between groups. Researchers suggest that alpha-lipoic acid may be clinically meaningful as a treatment for diabetic polyneuropathy.
A small, prospective, randomized, double-blind evaluation was done using 800 mg alpha-lipoic acid (ALA) or placebo on non-insulin dependent diabetes mellitus (NIDDM) patients with cardiac autonomic neuropathy. Subjects took one tablet four times daily of either 200 mg ALA (n=29) or placebo (n=35) for 4 months. Following 4 months of supplementation a decrease in heart rate variability (HRV) was seen in the ALA arm while a slight increase occurred in the placebo group, but he difference was not statistically significant. ALA does not appear effective in altering cardiac autonomic neuropathy, but additional studies should be performed.