Camellia sinensis (green tea) is used in traditional medicine to treat a wide range of ailments. In the present study, the insulin-releasing and glucose-lowering effects of the ethanol extract of Camellia sinensis (EECS), along with molecular mechanism/s of action, were investigated in vitro and in vivo. The insulin secretion was measured using clonal pancreatic BRIN BD11 β cells, and mouse islets. In vitro models examined the additional glucose-lowering properties of EECS, and 3T3L1 adipocytes were used to assess glucose uptake and insulin action. Non-toxic doses of EECS increased insulin secretion in a concentration-dependent manner, and this regulatory effect was similar to that of glucagon-like peptide 1 (GLP-1). The insulin release was further enhanced when combined with isobutylmethylxanthine (IBMX), tolbutamide or 30 mM KCl, but was decreased in the presence of verapamil, diazoxide and Ca²⁺ chelation. EECS also depolarized the β-cell membrane and elevated intracellular Ca²⁺, suggesting the involvement of a K_ATP-dependent pathway. Furthermore, EECS increased glucose uptake and insulin action in 3T3-L1 cells and inhibited dipeptidyl peptidase IV (DPP-IV) enzyme activity, starch digestion and protein glycation in vitro. Oral administration of EECS improved glucose tolerance and plasma insulin as well as inhibited plasma DPP-IV and increased active GLP-1 (7–36) levels in high-fat-diet-fed rats. Flavonoids and other phytochemicals present in EECS could be responsible for these effects. Further research on the mechanism of action of EECS compounds could lead to the development of cost-effective treatments for type 2 diabetes.

Diabetes mellitus, a major cause of mortality around the globe, can result in several secondary complications, including diabetic foot syndrome, which is brought on by diabetic neuropathy and ischemia. Approximately 15% of diabetic patients suffer from diabetic foot complications, and among them 25% are at risk of lower limb amputations. Diabetic foot ulcers are characterized as skin lesions, gangrene, or necrosis, and may develop due to several reasons, including hyperglycemia and slower wound healing in diabetic patients. A management protocol involving wound cleaning, oral antibiotics, skin ointments, and removing dead tissue is currently followed to treat diabetic foot ulcers. In severe cases, amputation is performed to prevent the infection from spreading further. The existing therapy can be costly and present adverse side effects. Combined with a lack of vascular surgeons, this ultimately results in disability, especially in developing nations. There is a growing interest in the use of alternative therapies, such as medicinal plants, to discover more efficient and affordable treatments for diabetic foot syndrome. It has been observed that treatment with numerous plants, including Carica papaya, Annona squamosa, Catharanthus roseus, and Centella asiatica, promotes wound healing, reduces inflammation, and may decrease the number of amputations. However, little information is currently available on the prevention and management of diabetic foot ulcers, and additional research is necessary to completely understand the role of alternative therapies in the treatment of diabetic foot complications.