Devil's Club (Oplopanax horridum) is an adaptogen with notable blood sugar balancing properties which is particularly useful in the treatment of those whose energy levels vary considerably throughout the day.

Useful for:
Diabetes mellitus
Improves concentration and endurance, ie memory loss
Improves stamina

Modern lab animal studies seem to support the traditional Native American uses of Devil's Club Root Bark:

Adaptogen
Antifatigue and Stimulant
CNS sedative
Hypoglycemic
Increases plasma levels of ACTH and corticosterone

http://www.ankn.uaf.edu/viereck/viereckdevilsclub.html:

The Kenai Tanainas boiled the stems and branches, then drank the resulting decoction for fever. The Upper Cook Inlet people boiled the inner bark of the underground portion of the plant and drank the tea for tuberculosis, stomach trouble, and colds as well as fever.

The same inner bark is said to have been a treatment for swollen glands as well as boils, sores and other external infections. After it was baked slowly until it was very dry, it was rubbed between the hands until it was broken and soft. This pulp was then placed on the affected area to draw out infection. (Kari)

The Chugach Eskimos of Prince William Sound employed the ashes of Oplopanax horridum to treat burns. (Birket-Smith, cited in Kari)

De Laguna states that devil's club was ''perhaps the most important medicinal and magical plant'' of the Yakutat Tlingit. The shaman as well as the layman chewed the stem bark (scraped of its thorns) for its emetic and purgative effects as well as for a general cure-all. These people also drank devil's club infusions and used the bark as poultices and on hot rocks in the bath house.

The Haida people were still using devil's club for a variety of complaints in 1965. (Justice, cited in Kari) They would mix the dried inner bark with cedar or spruce pitch for a waterproof dressing for wounds. Other groups of people on the Northwest Coast have used the plant for medicine and to obtain supernatural power.

The modern medical world has been interested in devil's club since the 1930s, due to the discovery of the possible presence of an insulinlike substance in the plant. It does seem to be of value in maintenance of diabetes but its chemistry is still under investigation. The therapeutic action is hypoglycemic. (Lewis) (Kari and Smith, unpublished).