Banaba (Lagerstroemia Speciosa)
In the Philippines, Banaba is a popular plant and is used for support in diabetes mellitus. Banaba has also been traditionally used to aid in cleansing the liver in the Philippines.
Banaba is high in corosolic acid, a “natural plant insulin”, which is used in many treatments for diabetes. It can be taken orally, and has no side effects, according to Japanese research.
Much research was done on Banaba leaves and their ability to reduce blood sugar, and its "insulin-like principle." Because of its ability to assist in regulating blood sugar within the normal range, it can be very useful in treatment of diabetes mellitus and weight control.
In Japan, Banaba tea has become quite popular and is known as "slimming tea." In the US, many weight-loss formulas are now using Banaba as a safe, natural component for reducing weight.
Following the studies done by the Japanese which isolated corosolic acid as the active component to control blood sugar, other studies followed which shown that the entire herb is useful in lowering blood sugar, and that corosolic acid is probably not the only active ingredient in Banaba leaves. They concluded that the whole herb had a glucose lowering effect and could be used to fight diabetes and obesity.
In addition, corosolic acid helps maintain low blood pressure and normal kidney function, by controlling blood sugar, and thus preventing damage to blood vessels and kidneys.
See http://www.lef.org/magazine/mag2000/sep2000_report_blood.html for a typical study confirming the blood glucose lowering effect of corosolic asid