Native to the Indian subcontinent, Gymnema has been used for over 2000 years as a diabetes remedy. Classical descriptions indicate gymnema for treatment of “honey urine” (the tasting of urine was common practice by doctors of the past in order to diagnose diabetic conditions). When the leaves of the plant are chewed, they interfere with the ability to taste sweetness; thereby it became known as gurmar, or ‘sugar destroyer’ in India. Because of this quality, gymnema has been marketed as an appetite suppressant and to promote weight loss. However, there is no evidence that gymnema has these effects. Taking capsules of gymnema will not alter one’s taste perception of sweetness; the leaves must be chewed directly in order to experience this sensation.
The applicable parts of this plant are its leaves. As mentioned, directly chewing on the leaves will temporarily block the ability to taste sweetness. This however, is not the typical administration for gymnema to exert its medicinal effects. Although this herb is used for conditions involving irregular metabolism of sugar, it is interesting that the sweet blocking ‘side effect’ of this herb occurs.
Gymnema has been used historically to treat diabetes, coughs, as a laxative, digestive stimulant, and as a snakebite antidote. Modern research has focused on the abilty of gymnema’s effects in diabetic conditions and thus remains the main application of this plant medicine today.
Gymnema is appropriate as an adjunctive diabetic treatment in several aspects, appearing to work via a combination of mechanisms. Primary research has shown that gymnema is able to increase the number of insulin-producing cells in the pancreas of laboratory animals, reestablishing normal blood sugar concentrations.  Gymnema can increase the metabolic activation of the enzymes that drive glucose absorption and utilization in the cells, thereby increasing the efficiency by which the body can use its primary fuel source.
Gymnema can also slow the use of glucose peripherally by other hormones in the body (somatotrophin and corticotrophin); this allows the serum levels of glucose to remain more stable in those with a propensity toward irregularities in blood sugar.  Taking gymnema may also slow the absorption of glucose, or sugar, from the intestine, thereby slowing the demand on the body for insulin production.  All of these effects make gymnema an effective diabetes adjunctive treatment.
Two constituents of gymnema leaves, gymnemic acid and gurmrin, are thought to be responsible for blocking the taste of sweetness; gymnema does not prevent the tasting of sour or astringent flavors. 
Varying doses have been suggested pertaining to recent research findings; however 400 to 600 milligrams per day is the most common dosage. [6, 7]
These studies do not describe frequency of dosage throughout the day; however due to the fact that this herb is taken to control blood sugar, divided doses throughout the day are recommended.
Gymnema Side Effects:
No side effects have been reported when using this herb, except for the expected decrease in blood sugar levels. The safety of gymnema has not been established in pregnancy and should therefore be avoided.
No interactions with other supplements, herbs, or foods have been reported when using gymnema. Taking gymnema prior to testing for blood glucose may cause fictitiously lower levels of this test.
Gymnema assists the body in lowering elevated blood sugar levels. Therefore, if one is diabetic and using any diabetes medications, including insulin, one should use caution if combing this herb with these medications.
Gymnema may lower blood sugar in diabetics; blood glucose should be closely monitored especially when administered with antidiabetes medications.
1 Shanmugasundaram ER, Gopinath KL. Shanmugasundaram KR, Rojendran VM. Possible regeneration of the islets of Langerhans in streptozotocin-diabetic rats given Gymnema sylvestre leaf extracts. J Ethnopharmacol 1990;30:265-279.
2 Shanmugasundaram KR, Panneerselvam C, Samudram P, Shanmugasundaram ER. Enzyme changes and glucose utilisation in diabetic rabbits: the effect of Gymnema sylvestre, R.Br. J Ethnopharmacol 1983;7:205-234.
3 Gupta SS, Variyar MC. Experimental studies on pituitary diabetes IV. Effect of Gymnema sylvestre and Coccinia indica against the hyperglycemia response of somatotropin and corticotrophin hormones. Indian J Med Res 1964;52:200-207.
4 Yeh GY, Eisenberg DM, Kaptchuk TJ, Phillips RS. Systematic review of herbs and dietary supplements for glycemic control in diabetes. Diabetes Care 2003;26:1277-94.
5 Katsukawa H, Imoto T, Ninomiya Y. Induction of salivary gurmarin-binding proteins in rats fed gymnema-containing diets. Chem Senses 1999;24:387-92.
6 Baskaran K, Kizar-Ahamath B, Shanmugasundaram MR, Shanmugasundaram ERB. Antidiabetic effect of leaf extract from Gymnema sylvestre in non-insulin-dependent diabetes mellitus patients. J Ethnopharmacol 1990;30:295-300.
7 No Authors Listed. Gymnema sylvestre. Altern Med Rev. 1999 Feb;4(1):46-7.