I. What is insulin? In the human pancreas, there are special cell aggregates scattered in the pancreas, like islets called islets. It consists of two chains, A and B. Insulin is an essential hormone that is normally secreted by the body, mainly regulating sugar metabolism. What are insulins? There are many kinds of insulins available in the market, and they are divided into human insulin and analogues according to their composition. Human insulin has the same structural composition as human insulin, while analogues such as menthol insulin and lysergic insulin are artificially biosynthesized insulins with certain modifications to certain structures of human insulin. There are also animal insulins, which are basically no longer used. According to the duration of action, it can be divided into fast-acting, short-acting, medium-acting and long-acting, such as fast-acting menthol insulin and lysergic insulin, short-acting human insulin, medium-acting human insulin such as arginine, long-acting insulin such as glargine, etc. There are also premixed insulins such as menthol insulin 30, which are easy to use, with a certain ratio of medium-acting and rapid-acting or short-acting. What is the role of insulin? Insulin mainly plays the role of regulating glucose metabolism in human body, that is, lowering blood sugar. Specifically, it includes the following aspects, promoting the conversion of glucose into energy; promoting the conversion of glucose into glycogen for storage. Promote the conversion of glucose into protein, fat, etc. IV. Under what circumstances is insulin used? 1.Temporary control of blood glucose in acute elevation of blood glucose. Such as diabetic ketoacidosis, hyperosmolar coma, serious infection, etc.; 2. Those with high blood glucose in initial diagnosis of type 2 diabetes. If glycosylated hemoglobin > 9% or fasting blood glucose > 11.1mmol/L, insulin therapy can be considered, which can partially restore pancreatic β-cell function, and even some patients can stop using any drugs for a period of time. 3.Patients with type 1 diabetes. Such patients have severe insulin deficiency and must be treated with insulin. 4.Patients with severe type 2 diabetes mellitus. Most of them have been suffering from type 2 diabetes for a long time, and some of them have been using pro-secretory agents for a long time and their pancreatic islets have failed, so they must also be treated with insulin. 5.Severe complications. Since insulin is exact in lowering sugar, for those with serious complications, strict control of blood sugar is necessary, and only insulin can be competent. 6.Insulin must also be used to control blood sugar during surgery and pregnancy.