Abstract: Free fatty acid receptor 1 (FFAR1), also known as G protein-coupled receptor 40 (GPR40), is a receptor for diverse free fatty acids. This review aims at summarizing effects and mechanisms of FFAR1 on insulin secretion and related blood glucose and lipids metabolism. FFAR1 is involved in the occurrence and development of type 2 diabetes, but its specific mechanism has not been clarified. FFAR1 is expressed in the wide variety of issues, especially β-cells in the pancreatic islets, as well as α-cells in islets, central nervous tissue, subcutaneous fat, skeletal muscle, gastrointestinal tract, etc. FFAR1 can act on islet β-cells to promote the secretion of insulin, promote α-cells on glucagon secretion, and regulate the secretion of endocrine cells in the gastrointestinal tract to balance the level of glucose and lipids. Existing research found that FFAR1 agonists have significant advantages. They promote insulin release, reduce weight and protect pancreatic β-cells, and have no risk of hypoglycemia. To in-depth understand the role of FFAR1 as a drug target in the treatment of diabetes, further pharmacological studies are still needed in order to obtain safer and more effective drugs against type 2 diabetes.