The antioxidant alpha-lipoic acid (ALA) in pill form improves diffuse nerve pain or “polyneuropathy” in patients with diabetes, researchers report in the journal Diabetes Care.

A recent pooled analysis showed that daily intravenous treatment with ALA could reduce pain and numbness in diabetic patients, the authors explain, but little work has been done to investigate the use of oral ALA.

Dr. Dan Ziegler from Heinrich Heine University, Duesseldorf, Germany and colleagues compared three doses of oral ALA to placebo in 166 patients with symptomatic diabetic polyneuropathy.

Mean total symptom scores and stabbing/lancinating and burning pain subscores were significantly reduced after 5 weeks in all active treatment arms compared with the placebo arm, the authors report.

ALA treatment had no measurable effect on numbness, the results indicate.

Symptoms improved significantly as early as 1 week with the highest ALA dose (1800 mg daily) and within 2 weeks with the other doses (600 mg and 1200 mg daily), the researchers note, and there were no significant differences among the three ALA groups for changes in mean total symptom score at any time point.

Nausea, vomiting, and dizziness were more common with ALA treatment than with placebo treatment.

Whether the observed favorable short-term effect of ALA on nerve pain and deficits can be translated into slowing the progression of diabetic polyneuropathy in the long term is unknown, the authors write.

“However, our finding that neuropathic deficits such as impaired sensory function were improved is encouraging, because these are major risk factors in the development of neuropathic foot ulcers.”

“In the absence of a dose response and because the higher doses resulted in increased rates of gastrointestinal side effects, 600 mg once daily seems to be the most appropriate oral dose,” the researchers add.

SOURCE: Diabetes Care November 2006.