Among the commonly used insulin injection sites, the abdominal wall has the fastest absorption rate. Subcutaneous injection of insulin is a commonly used treatment for diabetic patients. The commonly used injection sites for insulin include the abdominal wall, the outer upper arm, the outer thigh, and the buttocks, with the abdominal wall having the fastest absorption rate, the outer upper arm the second fastest, and the thighs and buttocks the slowest. Therefore, insulin that needs to be absorbed quickly and take effect should be injected subcutaneously in the abdominal wall. For example, preprandial insulin needs to be absorbed and peak as quickly as possible to avoid too high a rise in blood glucose after a meal. Basal insulin, such as intermediate-acting insulin, long-acting insulin, and long-acting insulin analogs, can be injected subcutaneously in the buttocks or outer thighs, which has a relatively slow absorption rate and no obvious peak value, and achieves the purpose of smooth blood glucose control. In addition, in the process of injecting insulin, attention should be paid to changing the injection site regularly, avoiding repeated injections in the same site, so as to avoid the formation of fat nodules or fat atrophy in the injection site, which will affect the absorption of insulin.