Herb drug Mix: Diabetes

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Fenugreek is one of several herbs that may effectively regulate blood sugar.
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Fenugreek is one of several herbs that may effectively regulate blood sugar.

Long before the discovery of insulin, European herbalists knew the benefits of an herb called goat’s rue (Galega officinalis). Although it’s unlikely that they understood its mechanism of action, these herbalists did know that goat’s rue could often treat the symptoms of a disease called diabetes mellitus. Not much was known about diabetes in those days except that it was a deadly disease that made the urine smell and taste sweet.

We now know that diabetes mellitus comes in two forms: type I, which results from a deficiency of insulin, and type II, which results from a defect in the receptors for insulin. In both cases, glucose can’t be adequately transferred into the cells of the liver, muscles, and fat tissues. As a consequence, it builds up in the bloodstream, where it inflicts progressive damage on nerves, blood vessels, and organs such as the eyes and kidneys.

Occurring primarily in people over forty, type II diabetes is by far the most common of the two forms. In fact, the United States has seen a virtual epidemic of cases over the past few decades–an epidemic that most experts attribute to a diet high in refined carbohydrates and low in fiber and phytochemicals such as bioflavonoids.

Chemical and herbal treatments

Pharmacologic analysis eventually showed that goat’s rue contained a substance called guanidine, which has a potent ability to lower blood sugar in type II diabetics. Unfortunately, guanidine turned out to be too toxic for long-term use and had to be abandoned. However, further research led to the creation of a chemical derivative of guanidine (called metformin), which proved to be much safer and reasonably effective. Metformin is now one of an entire class of drugs called hypoglycemic agents–examples of these drugs include chlorpropamide, glyburide, glypizide, and pioglitazone hydrochloride. Used in conjunction with dietary modification, these drugs are considered to be the standard of care for type II diabetes.

In a scenario that’s fairly typical of Western medicine, the more the experts focus on drug therapy for a particular disease, the less interested they become in natural alternatives. This is certainly the case with diabetes mellitus. There is evidence that numerous herbs can effectively but gently regulate blood sugar, or, in medical parlance, “improve glucose tolerance.” Examples of these herbs include American and Asian ginseng (Panax quinquefolius and Panax ginseng), fenugreek (Trigonella foenum-graecum), gymnema (Gymnema sylvestre), bitter melon (Momordica charantia), and aloe (Aloe vera).

Could the herbs be dangerous?

All of these herbs have a long history of use by traditional healers the world over, and none of them have been reported to cause significant side effects when used appropriately. Despite this, these herbs are not viewed in the medical literature as agents that could potentially enhance conventional treatment, but instead as sources of potential “negative interactions” with medications–interactions that could drop blood sugar to dangerously low levels.

In a 1998 Archives of Internal Medicine article, a prominent pharmacologist warned, “The use of these herbal medicinals in patients with diabetes, especially those with brittle diabetes, should be avoided.”

Why, you might wonder, are these effects automatically seen as interfering with conventional therapy? What prevents the experts from recognizing the advantage that these herbs offer? Wouldn’t it be a reasonable goal to allow the patient to lower their dose of the drug or reduce their insulin requirement?

Other references suggest that herbs could counteract the effects of anti-diabetic drugs through their “hyperglycemic” effects (meaning that these herbs supposedly raise blood sugar). The herbs thought to have hyperglycemic effects are cocoa bean (Theobroma cacao), rosemary (Rosmarinus officinalis), and nettle (Urtica dioica).

Although problems with these herbs were only reported in a case study, my concern is that, despite the flimsy evidence to support its veracity, this “interaction” has now been published in a widely distributed newsletter (Alternative Medicine Alert), which will no doubt be quoted by authorities wishing to point out the dangers of herbal medicines. (For the record, I don’t see any good reason for diabetic patients on oral hypoglycemics to avoid ingesting reasonable quantities of these herbs– it’s refined carbohydrates that they should be avoiding!)

The scientific research

Fortunately, misinformation about herbs that does become reported is balanced by some excellent scientific research conducted at major universities. For example, one recent published study, also from the Archives of Internal Medicine, looked at the effects of a 3-g dose of American ginseng on ten normal subjects and nine subjects with type II diabetes. The study found that when the ginseng was given forty minutes before a meal containing a large amount of glucose, it prevented the usual rise in blood sugar that occurs after a meal (a rise that is typically higher for people with diabetes).

Interestingly, the study also showed that when the ginseng was given with the meal, it prevented the rise in blood sugar in diabetic subjects only, not in normal people. The implications of this study were clear–American ginseng should be seriously considered as a legitimate agent for managing type II diabetes. (A secondary implication is that nondiabetics should take ginseng with meals to avoid hypoglycemia.)

The future of herbs

My hope is that we will continue to see more research of this caliber. It’s the only way we will be able to transcend the current trend of “herb-bashing.” This attitude shifts attention away from important issues such as the high cost and sometimes poor safety profile of pharmaceutical drugs and instead incites paranoia that herbal medicines will interfere with the beneficial effects of medications.

Although I don’t deny that negative interactions exist, it’s important for us to stop making generalizations based on poor data and get down to the facts. In the case of type II diabetes, the fact is that many of the herbs that have traditionally been prescribed for its management deserve equal consideration alongside conventional drugs, either as supportive agents or as a legitimate treatment for the disease.


Vuksan, V., et al. “American ginseng (Panax quinquefolius) reduces postprandial glycemia in nondiabetic subjects and subjects with type 2 diabetes mellitus.” Archives of Internal Medicine 2000, 160(7): 1009-1013.

Robert Rountree, M.D., is a physician at the Helios Health Center in Boulder, Colorado, where he practices integrative medicine. He is coauthor of both Smart Medicine for a Healthier Child (Avery, 1994) and Immunotics (Putnam, 2000), and is an Herb Research Foundation advisory board member.

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