Research progress on the antidiabetic activities of tea and its bioactive components

Diabetes mellitus (DM) is a pressing global public health issue with a high incidence of morbidity and mortality due to its complications. Although there are many medicines available for the treatment of DM, long-term use causes various adverse effects, such as diarrhea, vomiting, and nausea. Tea, owing to its richness of diverse bioactive components including tea polyphenols, tea polysaccharides, and alkaloids, has displayed promising antidiabetic properties. Screening antidiabetic bioactive compounds derived from teas is receiving increasing attention. Epidemiological and clinical investigations have demonstrated an inverse relationship between tea consumption and the incidence of DM. Both in vitro and in vivo experiments have substantiated the hypoglycemic effects of tea and its bioactive components through several possible mechanisms, including improvement of insulin resistance, inhibition of carbohydrates digestion and absorption (inhibit α-amylase and α-glucosidase activity), regulations of gut microbiota, inflammatory cytokines, and gene and protein expressions in insulin signaling pathway, as well as amelioration of DM complications. This comprehensive review provides an up-to-date overview of the hypoglycemic properties associated with tea and its bioactive components. It also delves into their potential mechanisms, offering a theoretical foundation for further research into tea's antidiabetic properties and for the development of innovative antidiabetic functional products.