Rapid-acting insulin, also known as insulin analogs, is a product of modifying part of the structure of insulin so that insulin is absorbed rapidly after injection, with faster onset of action and shorter time to peak. After subcutaneous injection of rapid-acting insulin, it usually takes 5-10 minutes to take effect and can reach its peak effect in about 1 hour, and the effect can last for 2-4 hours. Rapid-acting insulins are also called ultra-short-acting insulins, commonly used such as menthol insulin injection and lysergic insulin injection. The onset of action of menthol insulin injection is 10-15 minutes, with a peak time of 1-2 hours and a duration of 4-6 hours. Lysergic insulin has an onset of action of 10-15 minutes, a peak time of 1-1.5 hours, and a duration of 4-5 hours, and is clear in appearance. Fast-acting insulin is mostly injected before meals and is mainly used to control postprandial blood glucose at each meal. The injection method of rapid-acting insulin is more flexible, and it can be injected subcutaneously before, during or even immediately after a meal, although it is usually chosen to be injected before a meal.