Curcumin improves glucose tolerance via stimulation of glucagon‐like peptide‐1 secretion

Scope Glucagon‐like peptide‐1 (GLP‐1) is a type of incretin secreted from enteroendocrine L‐cells. Our previous studies demonstrated that curcumin (a yellow pigment of turmeric) significantly increases the secretion of GLP‐1 in enteroendocrine L cell line (GLUTag cells). However, it is not clear whether its action in vivo directly enhances GLP‐1 secretion, which then leads to a reduction in blood glucose levels via the stimulation of insulin secretion. In addition, the molecular target of curcumin‐induced GLP‐1 secretion has not been clarified. Methods and results Glucose tolerance was significantly improved in rats after pre‐administered curcumin (1.5 mg/kg) followed by intraperitoneal glucose injections via the stimulation of GLP‐1 secretion and the induction of insulin secretion. In GLUTag cells, curcumin‐induced GLP‐1 secretion was associated with G protein‐coupled receptor (GPR) 40/120. Furthermore, the glucose‐lowering effect induced by curcumin was significantly reduced after the administration of a GPR40/120 antagonist in rats. Conclusion These findings demonstrate the biological function of curcumin as a GLP‐1 secretagogue and the possible molecular target that mediates GLP‐1 secretion. Increases in the secretion of endogenous GLP‐1 induced by curcumin may allow the dosages of other diabetic medicines to be reduced and aid in the prevention of diabetes.