Insulin is a protein hormone secreted by pancreatic β-cells in the pancreas stimulated by endogenous or exogenous substances such as glucose, lactose, ribose, arginine, glucagon, etc., which can effectively control elevated blood glucose. Whether insulin is used for life depends on the function of pancreas, when the function of pancreas is gradually recovered, it can be switched to oral drugs to control blood glucose; if the function of pancreas is poor, such as type 1 diabetes mellitus, it needs to be used for life, and in addition, if there are contraindications to oral drugs, it needs to be used for life for insulin to control blood glucose.