Bitter melon is a perennial plant found in Asia, South America, East Africa, and the Caribbean. The edible fruit is used both as food and in medicine to treat diabetes, cancer, viral infections, and immune disorders.
Several active substances in bitter melon may act in a way similar to insulin. However, high-quality studies are needed to determine safety and effectiveness, and it cannot be recommended as a replacement therapy for insulin or hypoglycemic drugs.
Human studies on its effects on cancer are also lacking. One study showed it had no effect on the immune system of cervical cancer patients.