Insulin is an injectable drug to lower blood sugar. Insulin is an important method to control blood sugar for diabetic patients, and insulin can only be injected, not taken orally. There are many types of insulins, and they can be divided into short-acting insulin, intermediate-acting insulin, long-acting insulin, and insulin analogs based on their duration of action. Regular insulin, also known as short-acting insulin, regular insulin, regular insulin, etc., belongs to short-acting insulin in terms of duration of action. Regular insulin takes effect half an hour after subcutaneous injection, with a peak effect of 2-4 hours and lasts 4-6 hours, so regular insulin can be injected subcutaneously half an hour before a meal and can be used to control postprandial blood sugar of the corresponding meal. In most cases, regular insulin needs to be used in combination with basal insulin to effectively control fasting blood glucose and postprandial blood glucose. In addition, regular insulin is the only insulin that can be injected intravenously. When acute complications such as ketoacidosis and hyperosmolar coma occur in diabetic patients, regular insulin can be used intravenously to control blood glucose as soon as possible.