Clinical Briefs
With Comments from John La Puma, MD, FACP
American Ginseng for Postprandial Glycemia
July 2000; Volume 3; 83
Source:Vuksan V, et al. American ginseng (Panax quinquefolius L.) reduces postprandial glycemia in nondiabetic subjects and subjects with type 2 diabetes Arch Intern Med 2000;160:1009-1013.
Despite a lack of medical evidence to support its therapeutic efficacy, the use of herbal medicine has increased considerably. Ginseng, one of the most widely used herbs, is hypothesized to play a role in carbohydrate metabolism and diabetes mellitus. We therefore undertook a preliminary short-term clinical study to assess whether American ginseng (Panax quinquefolius L.) affects postprandial glycemia in humans.
On four separate occasions, 10 nondiabetic subjects (mean [+/-SD] age, 34 +/-7 years; mean [+/-SD] body mass index [BMI], 25.6 +/-3 kg/m2) and nine subjects with type 2 diabetes mellitus (mean [+/-SD] age, 62 +/-7 years; mean [+/-SD] BMI, 29 +/-5 kg/m2; mean [+/-SD] glycosylated hemoglobin A1c, 0.08 +/-0.005) were randomized to receive 3 g ginseng or placebo capsules, either 40 minutes before or together with a 25-g oral glucose challenge. The placebo capsules contained corn flour, in which the quantity of carbohydrate and appearance matched the ginseng capsules. A capillary blood sample was taken fasting and then at 15, 30, 45, 60, 90, and 120 (only for subjects with type 2 diabetes mellitus) minutes after the glucose challenge.
In nondiabetic subjects, no differences were found in postprandial glycemia between placebo and ginseng when administered together with the glucose challenge. When ginseng was taken 40 minutes before the glucose challenge, significant reductions were observed (P < 0.05). In subjects with type 2 diabetes mellitus, the same was true whether capsules were taken before or together with the glucose challenge (P < 0.05). Reductions in area under the glycemic curve were 18% +/-31% for nondiabetic subjects and 19% +/-22% and 22% +/-17% for subjects with type 2 diabetes mellitus administered before or together with the glucose challenge, respectively.
American ginseng attenuated postprandial glycemia in both study groups. To prevent unintended hypoglycemia, it may be important that nondiabetic subjects take American ginseng with the meal.
COMMENT
The seemingly paradoxical combo of ginseng inside sugary drinks, from new age beverages to evocative 2.3 ounce bottles sold in Asian markets, may have some basis in science. Maybe a little ginseng makes the sugar go down.
Usually prescribed as a tonic to relieve fatigue, boost energy, improve concentration, and increase work capacity, ginseng has been used for millennia, and is available in Germany by prescription, though not intended for diabetes.
With the explosion of type 2 diabetes (and parallel rise in obesity), something is needed to attenuate postprandial glycemia—especially hyperglycemia. These investigators capitalized on basic research to suggest just that effect, and in both controls and diabetics, postprandial glycemia was lessened when ginseng was taken before a glucose load, and in diabetics, also when taken with the glucose load.
American ginseng (P. quinquefolius) is reported to be milder than Asian ginseng (P. ginseng). Both contain ginsenosides, reportedly the active chemicals, especially ginsenoside Rb-1, which reportedly decreases islet cell insulin concentrations. Most of the adverse effects reported occur with Asian ginseng, not American ginseng, the wild variety of which is now an endangered species. Both American and Asian ginseng come in whole root, powders, tinctures, capsules, tablets, teas, and extracts. Ginseng’s interaction with antiplatelet/anticoagulant drugs is increasingly well-known.
Many patients—especially those at risk for bleeding, pregnant, or hypertensive—will have contraindications to ginseng use. Nothing is known about long-term ginseng use for diabetes control, though others have found favorable effects of Asian ginseng on hemoglobin A1c levels. This pilot study, like all good ones, raises more questions than it answers.
Recommendation
Suspect ginseng interaction with glipizide, glyburide, metformin, and the two glitazones remaining on the market—especially if blood sugars seem erratic. This pilot study is a good reason for better research on this subject. Included in the next trial should be a placebo arm and an arm for those who adhere to a weight-lowering, fitness-improving regimen.
July 2000; Volume 3; 83
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