The main role of insulin is to regulate blood glucose, which not only promotes the uptake and utilization of glucose by tissue cells throughout the body, but also inhibits the processes of glycogenolysis and glycogen isomerization, thus lowering blood glucose. Insulin is produced by human pancreatic islet β-cells, and the rate of its synthesis is related to plasma glucose concentration. Insulin can both inhibit the production of endogenous glucose and accelerate the conversion of exogenous glucose to maintain the stability of blood glucose in the body. When the blood glucose concentration is high, insulin will first inhibit glycogen phosphorylase inside the liver, thus directly restricting the output of glucose from the liver to the human blood, and endogenously reducing the production of glucose; at the same time, it will accelerate the rate of glucose transfer from the blood into the inside of the cells, and convert glucose into glycogen for storage, thus lowering blood glucose. It is necessary to avoid hypoglycemia when using exogenous insulin, and to apply insulin therapy appropriately under the guidance of a doctor while monitoring blood glucose changes.