Olive Leaf Extract of Olea europaea Reduces Blood Glucose Level through Inhibition of AS160 in Diabetic Rats

Introduction: It has been shown that olive leaf extract exerts (OLE) a positive effect on lipid and blood glucose levels; however, the mechanism remains poorly understood. This study aimed to examine the mechanism behind this effect by evaluating the proteins related to glucose metabolism, including glucose transporter 4 (Glut4), Akt Substrate of 160 kDa (AS160), and adenosine monophosphate-activated protein kinase (AMPK α2). Methods: Eighty-four male Sprague–Dawley rats were divided into three major groups: group one (control); group two, which was treated with OLE or metformin (Met.) before streptozotocin (STZ) injection; and group three, which was treated with OLE or Met. after STZ injection. The body weights, fasting blood sugar, postprandial sugar levels, insulin levels, and lipid profile were assessed. Western blot was used to measure the Glut4, AS160, and AMPKα 2 levels. Results: Treatments with (1% and 3% OLE) significantly decreased the glucose level, AS160 expression level, and STZ toxicity; additionally, insulin levels were maintained within the normal range and similar to Met. treatment. Conclusions: These findings indicated that OLE exerted antihyperglycemic effects via AS160 inhibition and it could be used as an alternative to Met. treatment. Further studies on the long-term effects of OLE on diabetes are warranted.