– Increases activities of the enzymes which facilitate use of glucose by insulin dependent pathways 
– Increases the uptake of glucose into glycogen and protein in liver, kidney and muscle 
Gymnema corrected the hyperglycemia in mild alloxan diabetic rats and prolonged life-span in severe alloxan diabetic rats. 
Gymnema extract and gymnemic acid significantly depressed the portal release of gastric inhibitory peptide after intraduodenal glucose infusion. They may be interacting with a glucose receptor which exists for the release of gastric inhibitory peptide. 
The gymnemic acids are considered to be the antisweet principles, but a peptide (gurmarin) has been isolated with significant antisweet activity. 
Two recent pharmacological studies have provided clear evidence for the benefits of Gymnema in diabetic models. In a Japanese study on mildly diabetic rats, 28 days of Gymnema use reduced post-prandial serum glucose and improved glucose tolerance. 
Two long-term Indian studies without placebo controls yielded promising results in diabetic patients. The first study on insulin-dependent diabetes mellitus found that Gymnema extract reduced insulin requirements and fasting blood glucose, glycosylated haemoglobin and glycosylated plasma protein levels. There was some suggestion of enhancement of endogenous insulin production, possibly by pancreatic regeneration. 
Studies have revealed that insulin-dependent diabetes mellitus (IDDM) patients taking oral medications could reduce their blood sugar levels significantly by taking 400 milligrams of gymnema sylvestre extract daily. 
The second study by the same research group on non-insulin- dependent diabetics found Gymnema extract produced similar results to the above study and hypoglycaemic drug requirements were reduced. Fasting and post-prandial serum insulin levels were elevated in the Gymnema group compared to controls taking only conventional drugs. 
Clinical research under double blind condition found that gymnemic acid considerably diminished the sweet taste. However, the study also revealed that gymnemic acid also significantly decreased appetite for up to 90 minutes after the sweet-numbing effect.
Gymnema anaesthetizes the sweet taste buds, an effect which can last many hours. This may have implications, both subtle and obvious, in weight control and dieting. 
It may be useful for athletes in developing a higher ratio of muscle mass to body fat because of the increased insulin output with long-term use.
Hypoglycaemic, Antidiabetic, Hypocholesterolaemic
Some cases of diabetes will respond quickly but best results come after six to twelve months of continuous use. It can be used to reduce sweet cravings and appetite.
Gymnema is usually taken at a dosage of 400 to 600 mg daily.
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suppressive effect on the neural responses to sweet taste stimuli in the rat. Comp Biochem Physiol A, 1991. 100(2): p. 309-14.
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