Nerve damage is one of diabetes’ most devastating complications and affects more than 50 percent of all diabetics. Its typical course is relentlessly downhill and there are no effective medicines to treat it. But now there is hope. A study recently published in Diabetes Care reports that the antioxidant nutrient alpha-lipoic acid (ALA) can partly restore diabetic nerve function after only four months of high-dose oral treatment.
One possible reason for the prevalence of diabetic neuropathy is that the elevated blood sugar levels associated with diabetes can distort normal metabolism and may, in turn, increase oxidative stress and free-radical production. High blood sugar, however, is apparently not the only culprit. Substantial evidence suggests that most diabetics are subject to high oxidative stress even when they control their blood sugar.
Animal studies suggesting that the free-radical scavenger ALA could prevent or reverse nerve damage motivated this careful, double-blind study.
A German research team studied people with diabetes who had damaged autonomic nervous systems (the nerves that control involuntary bodily functions such as heartbeat). To determine eligibility, the researchers tested patients’ autonomic nervous system damage with a special heart-monitoring test called spectral analysis. Seventy-three adult-onset diabetics from seven German medical centers were ultimately selected and randomly assigned to receive either 800 mg/day of ALA or a placebo. Repeat spectral analysis was done after four months.
At the study’s end, the spectral analysis showed continuing deterioration of both the sympathetic and parasympathetic systems of the placebo group. Patients taking ALA, however, had a statistically significant improvement in the sympathetic system and no change for the parasympathetic. Symptoms due to autonomic nerve disorder increased in the placebo group, but decreased with ALA.
This study provides the first clear evidence that nutritional treatment alone can reverse the course of autonomic neuropathy. The degree of improvement was modest, and the dose of ALA used was large and therefore expensive. We should, however, remember that diabetic neuropathy develops over many years. It is impressive that just four months of treatment resulted in any improvement at all.
ALA’s powerful antioxidant effect may be one way it helps heal a diabetic person’s damaged nerves. The healing effect could also be related to ALA’s ability to activate key enzymes in the pathways that convert glucose, fatty acids and other energy sources into ATP – the body’s main energy-storage and transport molecule.
ALA is the second nutrient proven effective for treating diabetic neuropathy. Recently, this column (March 1996 NSN) discussed a year-long, double-blind study indicating that primrose oil can reverse diabetic damage to peripheral (as opposed to autonomic) nerves. Primrose oil, and other sources of gamma linolenic acid such as borage or black currant seed oil, help balance the body’s prostaglandin levels and reduce inflammation. Animal studies and at least one small trial in humans suggest that ALA may also be effective for treating peripheral nerve damage.
Diabetics with autonomic neuropathy are five times more likely to die early than diabetics with healthy nervous systems. A damaged nervous system may render them more susceptible to heart disease, poor wound healing and infection – dangerous conditions that ALA promises to prevent.