Two supplements may benefit diabetic patients.
Data are accumulating to support the use of alpha-lipoic acid (ALA) in the treatment of diabetic neuropathy, and chromium as an adjunct to glucose- and lipid-lowering medications, said Dr. Shane-McWhorter, who is both a pharmacist and a certified diabetes educator at the University of Utah, Salt Lake City.
This is a natural coenzyme found in the body; it is involved in energy production and has been used in Germany for decades as standard therapy for neuropathy. It is thought to reduce oxidative stress caused by increased blood glucose, the process believed to underlie many of the microvascular and neuropathic complications of diabetes. Side effects include mild and dose-related gastrointestinal disturbances and possible hypoglycemia when used with sulfonylureas.
Unlike many of the botanicals used to treat diabetes, alpha-lipoic acid has a large body of data from well-conducted studies behind it.
A recent metaanalysis of four large, randomized, double-blind, placebo-controlled, parallel-group trials investigated the efficacy and safety of 600 mg of ALA given intravenously daily (except weekends) for 3 weeks to a total of 716 diabetic patients with symptomatic polyneuropathy.
The data also included 542 patients who received placebo (Diabet. Med. 2004;21:114-21).
After 3 weeks, the relative difference in favor of ALA over placebo was 24% in total symptom score (pain, burning, paresthesia, numbness) and 16% for the neuropathy impairment score of the lower limbs.
Overall responder rates were 53% in patients treated with ALA compared with 37% with placebo, a significant difference. The rates of adverse events did not differ between the groups.
In a smaller placebo-controlled trial involving a total of 65 diabetic patients with symptomatic polyneuropathy, improvements were seen at 24 months among those receiving ALA--given intravenously for the first 5 days, then orally thereafter in daily doses of either 600 or 1,200 mg. The improvements occurred in individual measures of nerve conduction, including sensory nerve conduction velocity, tibial motor nerve distal latency, and sensory nerve action potential.
There was no significant change in hemoglobin [A.sub.1c], however (Free Radic. Res. 1999;31:171-9).
Long-term trials will be necessary to determine whether ALA merely alleviates symptoms of diabetic neuropathy or actually slows its progression.
"This is a product that definitely warrants some close attention," Dr. Shane-McWhorter said.
This metal has become quite popular recently. Its trivalent form appears to work as an insulin sensitizer by increasing the number of insulin receptors in addition to other activities at the cellular level.
There is also a suggestion that the use of chromium in combination with biotin may increase its efficacy. It has been used to improve lipid levels, to induce weight loss, and for its ergogenic effects.
Side effects mentioned in case reports include renal toxicity, psychiatric problems, and rhabdomyolysis, but only at extremely high doses. Chromium could potentially cause hypoglycemia when used with other glucose-lowering agents. Its use in combination with other chromium-containing herbs, such as horsetail or cascara, could lead to chromium toxicity, Moreover, high doses of vitamin C and nonsteroidal anti-inflammatory agents can increase the absorption of chromium, whereas [H.sub.2]-blockers and proton-pump inhibitors may decrease it.
Steroids can also increase the excretion of chromium, which is one of the putative mechanisms by which steroids cause hyperglycemia, Dr. Shane-McWhorter noted.
In a widely quoted study, 155 subjects with type 2 diabetes received either 200 mcg or 1,000 mcg (1 mg) of chromium picolinate per day, along with their regular diabetes medications. At 4 months, hemoglobin [A.sub.1c] had declined by 2.8% among the patients taking 1,000 mcg and by 1.9% for those taking 200 mcg, compared with a reduction of only 0.5% for those on placebo (Diabetes 1997;46:1786-91).
This study was done in an area of China known to be deficient in chromium, which raises the question of whether supplementation works only in individuals who are chromium deficient--which many diabetic patients are, she noted.
One problem with answering that question is that there is no standardized way of measuring body stores of chromium. However, toenails appear to be a particularly sensitive area. In one recent study, toenail chromium concentration was inversely associated with the risk of a first myocardial infarction in men (Am. J. Epidemiol. 2005;162: 157-64).
Although chromium appears to be a promising agent for diabetic patients, its long-term effects are not known, Dr. Shane-McWhorter cautioned.
BY MIRIAM E. TUCKER
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|Author:||Tucker, Miriam E.|
|Publication:||Internal Medicine News|
|Date:||Oct 15, 2005|
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