Insulin is a protein hormone secreted by the islet beta cells in the pancreas. Insulin is involved in regulating sugar metabolism, controlling blood sugar balance, and can be used to treat diabetes. Its molecular weight is 5808 Daltons. Insulin is a protein hormone secreted by pancreatic beta cells when stimulated by endogenous or exogenous substances such as glucose, lactose, ribose, arginine, glucagon, etc. The first secretion is proinsulin, a long-chain polypeptide composed of 84 amino acids. Through the action of specific proteases, proinsulin convertase (PC1 and PC2) and carboxypeptide E, the middle part of proinsulin (Proinsulin) is secreted first. C chain) is cleaved, and the carboxyl-terminal part (A chain) and amino-terminal part (B chain) of proinsulin are joined together through disulfide bonds to form insulin. Mature insulin is stored in secretory vesicles in pancreatic beta cells and exists as a hexamer coordinated with zinc ions. Under external stimulation, insulin is released into the blood along with secretory vesicles and exerts its physiological effects.