Gymnema sylvestre (GS) is a woody climbing plant that grows in the tropical forests of central and southern India. The leaves are used in herbal medicine preparations. Gymnema sylvestre is known as "periploca of the woods" in English and mesbasringi (meaning "ram's horn") in Sanskrit. The leaves, when chewed, interfere with the ability to taste sweetness, which explains the Hindi name gurmar - "destroyer of sugar."
Gymnema sylvestre has been used in India for the treatment of diabetes for over 2,000 years. The primary application was for adult-onset diabetes, a condition for which it continues to be recommended today in India. The leaves were also used for stomach ailments, constipation, water retention, and liver disease.
Extracts of Gymnema sylvestre given to patients with type I diabetes on insulin therapy reduces insulin requirements and fasting blood sugar levels, and improves blood sugar control. In a study of type II diabetics, Gymnema sylvestre extract given along with oral hypoglycemic drugs was shown to improve blood sugar control and to either lead to discontinuation of the medicine or a significantly reduced dosage. Gymnema sylvestre is interesting to note that Gymnema sylvestre extract given to healthy volunteers does not produce any blood sugar-lowering, or hypoglycemic, effects.