ANTIDIABETIC ACTIVITY OF COFFEA ARABICA L.: A REVIEW OF IN-VITRO AND IN-VIVO EVIDENCE

Diabetes mellitus is a chronic metabolic disorder characterized mainly by high blood glucose levels caused by problems with insulin secretion, insulin action, or both. Coffee, particularly Coffea arabica L., contains several biologically active compounds such as chlorogenic acids, caffeine, trigonelline, caffeic acid, quinic acid, flavonoids and other phenolic compounds that may influence glucose metabolism. The antidiabetic potential of Coffea arabica L. has been investigated using coffee beans, green and roasted coffee, pulp and other coffee-processing by-products. In-vitro studies have reported inhibition of carbohydrate-digesting enzymes such as α-amylase and α-glucosidase, reduction of intestinal glucose transport, and changes in glucose transporter expression. Animal studies have also reported reductions in postprandial or diabetic blood glucose levels after treatment with selected coffee extracts or brewed Arabica coffee. However, the strength of the activity differs according to the plant material, extraction method, coffee origin, roasting condition, assay system and experimental model. The available evidence therefore supports the antidiabetic potential of Coffea arabica L. but further standardized in-vitro, animal and clinical studies are required before definite therapeutic conclusions can be made.