American ginseng may not only treat but also prevent diabetes. In a study at St. Michael’s Hospital at the University of Toronto in Canada, ginseng (3 g per day) lowered blood sugar and seemed to improve carbohydrate metabolism in nine people who had diabetes mellitus. This was true when it was taken either with a sugar solution or forty minutes beforehand. In nondiabetics, it altered blood sugar only when it was taken forty minutes before the sugar, but not with it. This suggests that nondiabetics, who generally do not want their blood sugar lowered, should take ginseng with food. The researchers say a long-term comprehensive clinical study is still needed to fully understand how ginseng works.
Source: 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.