In Chinese medicine, the Gardenia fruits extract is traditionally used to treat the symptoms of type 2 diabetes.

Recently, a research team found that a chemical from the Gardenia fruit blocks the action of an enzyme which stops the production of insulin. The new founding is that Gardenia extract contains the chemical called "genipin." This chemical is able to block the function and activity of the enzyme named uncoupling protein 2 (UCP2) through a special mechanism. As many studies have shown that an increase in UCP2 function has an important role in pathogenesis of diabetes, this genipin with its inhibitor action on UCP2, represents a solution for improving beta cell function in type 2 diabetes. Like the extract, Genipin stimulates the secretion of insulin in control but not UCP2-deficient pancreas. So it messes with the bodies natural ability to limit the production of insulin.

Uncoupling protein 2 (UCP2) negatively regulates insulin secretion. UCP2 deficiency improves obesity- and high glucose-induced beta cell dysfunction and was found to consequently improve type 2 diabetes in mice.

The action of genipin inhibits UCP2-mediated proton leak. In pancreatic islet cells, genipin increases mitochondrial membrane potential, increases ATP levels, closes K(ATP) channels, and stimulates insulin secretion. These consequences of genipin actions occur in a UCP2-dependent manner. Importantly, acute addition of genipin to isolated islets reverses high glucose- and obesity-induced beta cell dysfunction.