March 28, 2000 (Atlanta) -- They don't have to be tainted to be dangerous. That's what diabetes specialists suggest about dietary supplements touted as blood sugar-lowering agents. The advice comes just days after two more herbal products were pulled from the market because they contain "dangerously high" levels of a prescriptiondiabetes drug, glyburide.
The products, Dianolyn and Dimelstat, join five other herbal remedies pulled last month for the same reason -- except those products also contained phenformin -- a drug withdrawn from the U.S. market about 20 years ago because it caused a serious side effect.
Dianolyn and Dimelstat were both made by California firms, but FDA spokeswoman Laura Bradbard says they might be found anywhere. "These herbs were distributed beyond California, we can assume, because they were available through the Internet and by telephone order ... The products came from China."
Until recently, the Internet and China were unlikely avenues for diabetics to seek treatment. But point any browser to "herbal" and "diabetes" and up pop such items as Yu Xiao San, a product that claims the endorsement of three U.S. presidents and contains such items as winged ebony twigs, litchi seeds, and ginseng. Its manufacturer says it works to control blood sugar in more than 80% of cases -- and even claims it has an effect on type 1 diabetes, which can't be treated without insulin.
"It's distressing to us that these unproven claims are foisted on the public as if they are true," says Richard Forlanetto, MD, scientific director for the Juvenile Diabetes Foundation. "Once you develop [type 1] disease ... the herbs cannot replace insulin in any way." That's because insulin-producing cells in the body no longer work.
But the truth is, some herbs do lower blood sugar. "There are herbs that can be used to manage especially [type 2] insulin resistant diabetes," says June Reidlinger, PharmD, director of the Center for Integrative Therapies in Pharmaceutical Care at the Massachusetts College of Pharmacy in Boston. "But the majority are too toxic or have [only] mild effects" on blood sugar levels.
"The best one probably is gymnema," says Shiva Barton, ND, a naturopathic physician at Well Space in Cambridge, Mass. "It seems to be relatively effective." Blueberry leaf and fenugreek are also useful, he says -- but warns that any treatment should be supervised. "It's particularly important in diabetes that you have someone to help manage your care. Because you could get into problems with it."
What makes herbal remedies a gamble for diabetics is the exquisite control needed over their disease -- and the harsh consequences of letting things get out of hand. Uncontrolled diabetes can lead to blindness, gangrene, and numerous cardiovascular complications.
But some herbal marketers say what diabetics may really have to worry about is the prescription drug they're taking. They got some fresh ammunition for that argument last week when the antidiabetic drug Rezulin was withdrawn from the market. It has been linked to more than 60 deaths.
"Is our product safer than Rezulin? No question," says Nick Pokoluk, president of Golden Leaf Products in Moscow, Penn. The product he's referring to, Pancresan PFII, contains a mixture of Chinese herbs that Pokoluk says controls blood sugar and influences the "functionality" of insulin. He says the product is so safe that his wife and son -- both non-diabetics -- use it all the time.
"There are two problems with herbals," says Xavier Pi-Sunyer, MD, head of the division of endocrinology at St. Luke's-Roosevelt Hospital in New York. "One, they haven't been appropriately tested in general, so you really don't know how effective they are. Two, it's always very difficult to know how much of the ingredient is actually in there. These are not well-regulated substances."
Pi-Sunyer says he has "real skepticism" about recommending the use of antidiabetic herbs. "If patients do ask me, I try to dissuade them for this reason: I don't feel that as a physician I have the information to tell them it is good for them. It's just not there."
"Modern medicine is based on evidence -- placebo-controlled, double-blind studies," says Stanley Feld, MD, MACE, spokesman for the American Association of Clinical Endocrinologists. "I'm not aware of any double-blind placebo studies for [antidiabetic] herbals. I would use caution in believing any claims unless a double-blind study was performed."
Christopher M. Foley, MD, director of Integrative Health, HealthEast Care System in St. Paul, Minn, advocates the use of diet, exercise, and certain nutritional supplements including omega-3 fatty acids, magnesium, vanadium, and small doses of chromium. As for herbs in general: "I don't deny the fact that there are probably excellent Traditional Chinese Medicine practitioners," Foley says. "[But] even they will acknowledge they must have some control over the [herb prescribing] process."
But Feld offers an option for patients who want to take control over their disorder without the use of supplements. "There's a wonderful, nonmedical treatment for type 2 diabetes and that's called diet and exercise," he says. "Many diabetics who truly adhere to diet and exercise can achieve good control of their disease."
- Recently the FDA has pulled off the market some herbal supplements targeted to diabetics, but even other supplements that are still available may not be a wise choice.
- There may be some supplements that are effective, but no one should self-prescribe herbs.
- For nonmedical treatment of type 2 diabetes, diet and exercise can be effective, as can supplementation with omega-3 fatty acids, magnesium, vanadium, and small doses of chromium.