Introduction
Diabetes is an illness that damages many organs in the body,
including the heart and blood vessels, nerves, kidneys, and eyes. Most of this
damage is believed to be caused by the toxic effects of abnormally high blood
sugar, although other factors may play a role too.
Tight control of blood sugar greatly reduces all complications of diabetes. Some of the natural treatments described here also may help.
Principal Proposed Natural Treatments
Several dietary and herbal supplements may help prevent or treat some of the common complications of diabetes. However, because diabetes is a dangerous disease, alternative treatment should not be attempted as a substitute for conventional medical care.
Natural treatments helpful in general for improving cholesterol and
triglyceride profiles may be useful to people with diabetes. Contrary to some
early concerns, both fish oil and niacin
(treatments used for improving triglyceride and cholesterol levels, respectively)
appear to be safe for people with diabetes.
High levels of blood sugar can damage the nerves leading to the extremities, causing pain and numbness. This condition is called diabetic peripheral neuropathy. Nerve damage may also develop in the heart, a condition named cardiac autonomic neuropathy. Following is a discussion of three natural supplements–acetyl-L-carnitine, lipoic acid, and gamma-linolenic acid–that have shown promise for the treatment of diabetic nerve damage.
Acetyl-L-carnitine. The supplement acetyl-L-carnitine (ALC) has shown promise for diabetic peripheral neuropathy. Two fifty-two-week, double-blind, placebo-controlled studies involving 1,257 people with diabetic peripheral neuropathy evaluated the potential benefits of ALC taken at 500 milligrams (mg) or 1,000 mg daily. The results showed that the use of ALC, especially at the higher dose, improved sensory perception and decreased pain levels. In addition, the supplement appeared to promote nerve fiber regeneration. ALC has also shown some promise for cardiac autonomic neuropathy.
Lipoic acid. Lipoic acid is widely advocated for the
treatment of diabetic neuropathy. However, while there is meaningful evidence for
benefits with intravenous lipoic acid, there is only minimal evidence to indicate
that oral lipoic acid can help.
A double-blind, placebo-controlled study that enrolled 503 people with diabetic peripheral neuropathy found that intravenous lipoic acid helped reduce symptoms in a three-week period. However, when researchers substituted oral lipoic acid for intravenous lipoic acid, benefits ceased.
Benefits were seen with oral lipoic acid in a study published in 2006. In this double-blind, placebo-controlled trial, 181 people with diabetic peripheral neuropathy were given either placebo or one of three doses of lipoic acid: 600, 1,200, or 1,800 mg daily. During the five-week study period, benefits were seen in all three lipoic acid groups compared with the placebo group. However, while this outcome may sound promising, one feature of the results tends to reduce the faith one can put in them: the absence of a dose-related effect. Ordinarily, when a treatment is effective, higher doses produce relatively better results. When such a spectrum of outcomes is not observed, one wonders if something went wrong in the study.
Other than this one study, the positive evidence for oral lipoic acid in diabetic peripheral neuropathy is limited to open studies of minimal to no validity and to double-blind trials too small to be relied upon.
Lipoic acid has also been advocated for cardiac autonomic neuropathy, and one study did find benefits: The DEKAN (Deutsche Kardiale Autonome Neuropathie) study followed seventy-three people with cardiac autonomic neuropathy for four months. Treatment with 800 mg of oral lipoic acid daily showed significant improvement compared with placebo, and no important side effects. Preliminary evidence hints that lipoic acid may be more effective for neuropathy if it is combined with gamma-linolenic acid.
Gamma-linolenic acid. Gamma-linolenic acid (GLA) is an
essential fatty acid in the omega-6 category. The most common sources of GLA are
evening primrose oil, borage oil, and black currant oil.
Many studies in animals have shown that evening primrose oil can protect nerves from diabetes-induced injury. Human trials have also found benefits. A double-blind study followed 111 people with diabetes for one year. The results showed an improvement in subjective symptoms of peripheral neuropathy, such as pain and numbness, and objective signs of nerve injury. People with good blood sugar control improved the most. A much smaller double-blind study also reported positive results.
Other Proposed Natural Treatments
A four-month, double-blind, placebo-controlled trial found that
vitamin
E at a dose of 600 mg daily might improve symptoms of cardiac
autonomic neuropathy. Vitamin E and selenium have also shown promise for diabetic
peripheral neuropathy. Intriguing evidence from a small study suggests that
vitamin E may also help protect people with diabetes from developing damage to
their eyes and kidneys. However, a large, long-term study failed to find vitamin E
effective for preventing kidney damage. (Vitamin E also did not help prevent
coronary artery disease.) In a review of thirteen randomized trials, researchers
found inadequate evidence for the effectiveness of B vitamins for peripheral
neuropathies (diabetic or otherwise).
The supplement inositol has been tried as a treatment for diabetic neuropathy, but the results have been mixed. In preliminary studies, fish oil has shown some promise for diabetic neuropathy, but human trials have not been performed.
Diabetes can cause swelling of the ankles and feet by damaging small blood vessels (microangiopathy). A preliminary, double-blind, placebo-controlled trial suggests that oxerutins might be helpful for this condition.
Weak evidence suggests that the herb bilberry may help prevent eye damage (cataracts and retinopathy) caused by diabetes. Pycnogenol, a source of oligomeric proanthocyanidins (OPCs), has also shown promise for diabetic retinopathy.
It has been suggested that vitamin C may also help prevent
cataracts in diabetes, based on its relationship to sorbitol. Sorbitol, a
sugar-like substance that tends to accumulate in the cells of people with
diabetes, may play a role in the development of diabetic cataracts. Vitamin C
appears to help reduce sorbitol buildup, but the evidence that vitamin C provides
significant benefits by this route is indirect and far from conclusive. Another
study suggests that vitamin C might be helpful for reducing blood pressure in
people with diabetes. The herb Tinospora cordifolia and honey
(applied topically) have shown some promise for speeding healing of diabetic foot
ulcers.
Magnetic insoles, a form of magnet therapy, have shown some promise
for the treatment of diabetic peripheral neuropathy. A four-month, double-blind,
placebo-controlled, crossover study of nineteen people with peripheral neuropathy
found a significant reduction in symptoms in those using the insoles compared with
those using placebo insoles. This study enrolled people with peripheral neuropathy
of various causes; however, reduction in the symptoms of burning, numbness, and
tingling was especially marked in those cases of neuropathy associated with
diabetes.
Another type of magnetic therapy, involving low- frequency, repetitive magnetic pulses generated by an electric current, was no better than a placebo at relieving painful peripheral neuropathy among sixty-one people who had long-term diabetes. In another study, however, high-frequency magnetic fields applied repetitively to the brain were more effective than placebo in reducing pain and improving quality of life among twenty-eight subjects with peripheral neuropathy.
One small, double-blind, placebo-controlled study suggests that regular use of multivitamin-multimineral supplements may reduce the incidence of infectious illness in people with diabetes. Another study failed to find that general nutritional supplementation accelerated healing of diabetic foot ulcers.
Bibliography
Ang, C. D., et al. “Vitamin B for Treating Peripheral Neuropathy.” Cochrane Database of Systematic Reviews (2008): CD004573. Available through EBSCO DynaMed Systematic Literature Surveillance at http://www.ebscohost.com/dynamed.
Barringer, T. A., et al. “Effect of a Multivitamin and Mineral Supplement on Infection and Quality of Life.” Annals of Internal Medicine 138 (2003): 365-371.
Eneroth, M., et al. “Nutritional Supplementation for Diabetic Foot Ulcers.” Journal of Wound Care 13 (2004): 230-234.
Manzella, D., et al. “Chronic Administration of Pharmacologic Doses of Vitamin E Improves the Cardiac Autonomic Nervous System in Patients with Type 2 Diabetes.” American Journal of Clinical Nutrition 73 (2001): 1052-1057.
Montori, V. M., et al. “Fish Oil Supplementation in Type 2 Diabetes.” Diabetes Care 23 (2000): 1407-1415.
Purandare, H., and A. Supe. “Immunomodulatory Role of Tinospora cordifolia as an Adjuvant in Surgical Treatment of Diabetic Foot Ulcers.” Indian Journal of Medical Sciences 61 (2007): 347-355.
Shukrimi, A., et al. “A Comparative Study Between Honey and Povidone Iodine as Dressing Solution for Wagner Type II Diabetic Foot Ulcers.” Medical Journal of Malaysia 63 (2008): 44-46.
Wrobel, M. P., et al. “Impact of Low Frequency Pulsed Magnetic Fields on Pain Intensity, Quality of Life, and Sleep Disturbances in Patients with Painful Diabetic Polyneuropathy.” Diabetes and Metabolism 34 (2008): 349-354.
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