Charlene Laino

June 16, 2003

June 16, 2003 (New Orleans) — American and Korean red ginseng may help to normalize blood glucose levels and improve insulin secretion and sensitivity in patients with type 2 diabetes, two new studies suggest. University of Toronto investigators presented both trials here this weekend at the American Diabetes Association 63rd Scientific Sessions.

In one study, people with type 2 diabetes who consumed ginseng and Konjac mannan fiber (a highly viscous fiber similar to pectin) had a notable reduction in blood glucose levels, reported Alexandra Jenkins, BSc, RD, a research associate at the University of Toronto in Ontario.

The double-blind, placebo-controlled, crossover-designed study enrolled 30 well-controlled diabetes patients; 23 were receiving oral hypoglycemic agents, and seven used lifestyle intervention alone. The participants, who were kept on their standard diabetes regimen, were randomly assigned to receive either 3 g of ground-up North American–grown ginseng and 7 g of Konjac mannan fiber blend, or placebo, daily for 12 weeks.

By the end of the study period, hemoglobin A1c (HbA 1c) levels had dropped from an average baseline level of 7.0% to 6.5% in patients were taking the ginseng preparation compared with 6.8% for those who were taking placebo, Ms. Jenkins said.

"The drop is comparable to that seen with other hypoglycemic agents, such as the alpha-glucosidase inhibitors, when used as adjunct therapy," she said. The herbal preparation appeared to be safe, with no adverse effects observed, she said.

The results suggest that standard pharmacological therapies and ginseng are complementary in treating diabetes, said Francine R. Kaufman, MD, outgoing president of the American Diabetes Association. "The Chinese, who use ginseng root to treat a variety of ailments, have been in medicine for 5,000 years," she said. "Just as acupuncture has been proven to have a role in Western medicine, so too will ginseng. We need to think globally."

In the second study, Korean red ginseng improved both insulin secretion and insulin sensitivity when compared with placebo, reported John L. Sievenpiper, a PhD candidate at the University of Toronto. The trial enrolled 19 well-controlled diabetic patients, applying the same design used in the American ginseng study.

Korean red ginseng was safe, with liver, kidney, and hemostatic function and blood pressure not adversely affected compared with placebo, the study showed.

While HbA 1c levels did not significantly change, the ginseng preparation "was associated with a dramatic 40% drop in both postprandial plasma glucose and insulin levels," Mr. Sievenpiper said. Also, ginseng treatment led to a significant improvement in both hepatic insulin sensitivity and whole-body insulin sensitivity compared with placebo, he reported.

"The baseline HbA 1c levels were already at 6.5%, so we couldn't push it down significantly," he said. "But in patients with slightly higher levels, we might see an effect."

Dr. Kaufman, who is also head of the Center for Diabetes at Children's Hospital in Los Angeles, California, agreed. "There is no doubt that natural products such as ginseng have a role in modulating weight and insulin sensitivity," she said. But exactly "how adjunctive they may or may not be" still needs to be determined, she added.

Mr. Sievenpiper emphasized that "these are preliminary, short-term studies that indicate a need for more research. They are not a reason to recommend ginseng to patients," he said. And because of poor regulation, standardization, and labeling in the herbal industry, there is no way to know if one product will work as well as another, Mr. Sievenpiper said.

He pointed out that in a recent survey physicians estimated that three in four patients take complementary medicines, including herbs. Therefore, physicians should ask their diabetes patients if they are taking ginseng or other complementary therapies, because standard medication dosing may need to be adjusted.

The Korean red ginseng study was funded in part by the Korean Ministry of Agriculture and Forestry.

ADA 63rd Scientific Sessions: Poster 1676, presented June 14, 2003; poster 587, presented June 15, 2003.

Reviewed by Gary D. Vogin, MD

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