The botanical name of Gymnema is Gymnema Sylvestre. It is also known as Gurmar, Gurmabooti, Ram's Horn, Periploca of the woods and Meshasringi.
It is known as Periploca of the woods in English and Meshasringi - meaning ram's horn - in Sanskrit. The leaves, when chewed, effectively block sweet tastes in the mouth which explains the Hindi name Gurmar meaning "sugar destroyer".
A member of the milkweed family Gymnema Sylvestre is a woody climbing plant that grows in the tropical forests of central and southern India, Deccan peninsula, Assam, and some parts of Africa whose leaves are used in herbal medicine preparations.

History:
Indian physicians first used Gymnema to treat diabetes almost 2,000 years ago. The primary application was for adult-onset diabetes, a condition for a condition once described as "honey urine and is continued to be recommended today in India. The leaves were also used for stomach ailments, constipation, water retention, and liver disease.
In the 1920s, preliminary scientific studies found some evidence that Gymnema leaves can reduce blood sugar levels, but nothing much came of this observation for decades. Today, Gymnema has become increasingly popular in the United States as a supportive treatment for diabetes.

Active constituents:
Plant constituents include two resins (one soluble in alcohol), gymnemic acids, tartaric acid, gurmarin, calcium oxalate, glucose, saponins, stigmasterol, quercitol, and the amino acid derivatives betaine, choline and trimethylamine. Gymnema Sylvestre is a stomachic, diuretic, refrigerant, astringent, and tonic. It has been found to increase urine output and reduce hyperglycemia in both animal and human studies.

Usage of the herb:
Blood Sugar
The main focus of Gymnema research is blood sugar regulation and glucose metabolism. Several studies suggest that Gymnema can lower blood sugar levels in people with type 1 diabetes mellitus (insulin-dependent diabetes) and type 2 diabetes mellitus (non-insulin-dependent diabetes). The herb has shown to reduce blood sugar, glycosylated hemoglobin and glycosylated plasma proteins when used for 18-20 months. The effect is gradual rather than immediate with conventional drugs. The active components responsible for lowering glucose are the gymnemic acids.

Traditional Ayurvedic medicine uses Gymnema to treat a variety of other disorders as well, including digestion problems, cough, constipation, and malaria. Animal studies indicate a possible role for Gymnema in lowering cholesterol, triglycerides, and LDL ("bad") cholesterol.
Unproven Uses
Gymnema has been suggested for many other uses, based on tradition or on scientific theories. However, these uses have not been thoroughly studied in humans, and there is limited scientific evidence about safety or effectiveness. Some of these suggested uses are for conditions that are potentially serious and even life-threatening. You should consult a health care provider before using Gymnema for any unproven use.

Aphrodisiac

Cardiovascular disease

Cholesterol reduction

Constipation

Cough

Digestive stimulant

Diuretic

Gout

High blood pressure Laxative

Liver disease

Liver protection

Malaria

Obesity

Rheumatic arthritis

Snakebite antidote

Stomach disorders

Uterine stimulant

General Interaction:

Gymnema may alter the dosage needed for other drugs commonly used to treat diabetes, including glipizide, metformin, and insulin resulting in hypoglycemia.

Cautions:
Gymnema has safely been used for decades in various countries. Careful long-term studies on its safety have not been done so far, however.
Consult your doctor about your desire to supplement your diabetes regimen with Gymnema.

Ailments Dosage:
Diabetes: 150 mg twice a day
Warnings: Gymnema should not be taken in place of insulin. It could potentially lower blood sugar too much, resulting in a hypoglycemic reaction. If you have been diagnosed with diabetes and wish to use Gymnema consult your physician first. It should not be used as a substitute, only a supplement to your current therapy.

Allergies: People allergic to plants in the Asclepiadaceae (milkweed) family should avoid Gymnema.

Side Effects: Gymnema may lower blood sugar levels. Caution is advised if you are also taking prescription drugs that may lower blood sugar levels. Patients taking oral drugs for diabetes or using insulin should be monitored closely by their health care provider while using Gymnema. Dosing adjustments may be necessary. Gymnema may alter the ability to taste sweet foods.
Pregnancy and Breast-Feeding: Gymnema cannot be recommended during pregnancy or breast-feeding because of a lack of information on safety and effectiveness.
Summary
Although Gymnema has been suggested for multiple conditions, the best evidence supports its use in lowering blood sugar levels. Because this can be dangerous in individuals already taking prescription drugs that lower blood sugar levels, consult your health care provider before starting therapy. Pregnant or breast-feeding women should avoid Gymnema. Contact your health care provider immediately if you experience any side effects.