Insulin is the only hormone secreted by pancreatic beta cells in the body that can lower blood glucose and promote the synthesis of fat and protein, which can effectively block or delay the occurrence and development of various acute and chronic complications of diabetes. At present, there are first-generation animal (porcine/bovine) insulin, second-generation genetically synthesized human insulin and third-generation insulin analogues. The first generation insulins have poor efficacy and are prone to allergy or resistance. Second-generation insulins are more pure and have fewer side effects. The third generation insulins have better and safer blood glucose control, and are commonly used in clinical practice, such as rapid-acting menthol insulin, premixed menthol insulin 30 and long-acting glargine insulin. The Chinese Guidelines for the Prevention and Treatment of Type 2 Diabetes (2010 Edition) points out that Chinese patients with type 2 diabetes may have poorer islet function and are more prone to beta cell failure, so the use of insulin therapy at the early stage of diabetes onset is conducive to islet cell function recovery and blood glucose control, but some patients are “scared” of this. The truth is that the earlier insulin therapy is used, the better, and the earlier it is used, even if long-term injections are necessary for the condition. So, who needs to consider using insulin? One is a type 1 diabetic, the second is a type 2 diabetic whose HbAlc is still higher than 7% after multiple oral medications, and the third is a person who has lost weight without obvious reasons. Starting insulin therapy, the dosage can be adjusted according to the blood glucose monitoring, 1-4u each time until the blood glucose standard is reached, usually injecting rapid-acting or short-acting before meals, and injecting medium-acting or long-acting at night. It should be noted that unused insulin should be placed in an environment of 2-8℃, not to be injected before exercise, not to be injected during umbilical week, not to stop insulin injection or change insulin type casually, needles should be used once, preferably not more than 3 days (6 times), and attention should be paid to prevent the occurrence of hypoglycemia.