The Symptomatic Diabetic Neuropathy (SYDNEY) 2 trial compared once-daily dosing of alpha-lipoic acid (ALA) against placebo in 181 patients aged 18 to 74 years old with diabetic neuropathy. Diabetic neuropathy is damage to peripheral nerves as a result of diabetes. Nerve damage from diabetes occurs slowly over a period of years. Symptoms are usually slight and may go unnoticed for a long time. Numbness, tingling and pain in the feet or legs are often the first symptoms. Over time nerve damage can cause problems with the digestive tract and sexual organs as well as the lower extremities. Damage to digestive tract nerves can cause diarrhea or constipation and damage to sexual organ nerves can cause impotence. Damage to nerves in the feet can lead to loss of feeling which can contribute to injury going unnoticed and leading to ulcers, infections, and amputations.

The SYDNEY 2 trial compared ALA 600 mg/day, 1,200 mg/day, 1,800 mg/day or placebo for 5 weeks. The primary endpoint was change in Total Symptom Score (TSS) from baseline for each group. The TSS is a summation of four symptoms including stabbing pain, burning pain, paresthesia, and numbness of the feet. All 3 doses of ALA resulted in significant improvement in mean TSS compared with placebo. Side effects such as nausea, vomiting, and vertigo were reported and increased as the dose increased. These results indicate a 600 mg/day dose of ALA as the most appropriate oral dose for the treatment of diabetic neuropathy.

Alpha-lipoic acid was identified in the 1950's and recognized as an anti-oxidant in 1988. ALA plays a critical role in energy production within cells. The body makes enough ALA on its own for this basic function. When there is an excess of ALA, such as occurs with supplementation, it acts as an anti-oxidant. ALA has been purported useful for many age-related diseases including heart attack and stroke, Parkinson's disease and Alzheimer's disease. ALA is also being investigated for use in HIV and multiple sclerosis.

Diabetic patients may wish to discuss use of ALA at 600 mg/day to treat neuropathy with their doctor. Although ALA appears to be safe and effective, the long-term effects of supplementation are not known.

References: Zeolla, Mario M., Diabetic neuropathy: ALA useful, APhA DrugInfoLine, January 2007, vol. 8, no. 1.; http://www.ninds.nih.gov/disorders/diabetic/diabetic.htm; http://www.wellnessletter.com/html/ds/dsAlphaLipoicAcid.php.

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