Insulin can be bought in pharmacies. Insulin is a prescription drug and needs to be bought with a doctor’s prescription. Insulin has long-acting insulin, mixed insulin, short-acting insulin, etc. The dosage and usage of each dosage form are different, so you must buy it according to your doctor’s prescription and never change it privately. Unused insulin must be kept in a constant temperature and avoid violent vibration or bright light exposure. The shelf life of in-use insulin is 4 weeks when stored at room temperature within 25 degrees. Diabetic patients who inject insulin must pay attention to regular blood glucose testing and adjust the dose of insulin at any time to avoid causing hypoglycemic reactions, as well as pay attention to controlling diet, increasing exercise appropriately and maintaining a calm state of mind.