At least three different groups of constituents in bitter melon have been reported to have blood-sugar lowering actions of potential benefit in diabetes mellitus. These include a mixture of steroidal saponins known as charantin, insulin-like peptides, and alkaloids. It is still unclear which of these is most effective, or if all three work together. Some clinical trials have confirmed the benefit of bitter melon for people with diabetes.
In traditional herbal medicine, bitter melon,like other bitter-tasting herbs,is thought to stimulate digestive function and improve appetite. This has yet to be tested in human studies.