Banaba

Banaba - (no English) - Lagerstroemia Speciosa Linn. Parts used: leaves and bark
Banaba is a tree which is found throughout the Philippines, including Mt. Banahaw. There has been much resource done on Banaba leaves and their ability to reduce blood sugar, and its "insulin-like principle." In the Philippines, Banaba is a popular medicine plant and is used in treatment of diabetes mellitus. It is high in colosolic acid which is used in many drugs for diabetes. It is also used in weight-loss products. The leaves are also known to be diuretic and purgative. The bark is used to stop diarrhea.

Source: http://www.philippineherbs.com/philippineherbindex.htm