There are many types of insulin, which are categorized as follows according to their source and duration of action: 1. Classified according to the source of insulin (1) Animal insulin: insulin purified mainly from the pancreas of cattle or pigs, such as conventional insulin; (2) Human insulin: insulin synthesized through gene synthesis and human insulin molecular structure is identical, such as recombinant human insulin injection; (3) Insulin analogs: insulin produced by changing the amino acids in the molecular structure of insulin, mainly including menthyl insulin, glycemic insulin, dutasteride insulin and so on. 2. According to the characteristics of insulin action and fast and slow classification (1) Fast-acting insulin, commonly used in clinic are lysergic insulin and menthyl insulin; (2) short-acting insulin: such as conventional insulin, recombinant human insulin belongs to this type of insulin, commonly used in the clinic are biosynthesis human insulin injection; (3) Intermediate-acting insulin: commonly used in clinical practice, including low-arginine zinc insulin (NPH), recombinant human insulin (N) and so on; (4) Long-acting insulin: the duration of action is longer than that of intermediate-acting insulin, commonly used in clinical practice, including zinc fischer’s zinc insulin, glycemic insulin, dutasteride insulin, and Deguchi insulin; (5) Pre-mixed insulin: arginine biosynthesis human insulin injection (pre-mixed 30R), Mentholatum insulin 30 and so on. In conclusion, there are many types of insulin, which should be chosen and used according to medical advice.