It is not recommended to use insulin once it has expired, and there is no such thing as “how long after the expiration date should it not be used”. Insulin can be used to treat all types of type 1 diabetes and type 2 diabetes where dietary control is ineffective and glucose-lowering drugs are ineffective. Insulin can only play its maximum pharmacological effect within the expiration date, once the expiration date will be difficult to play a good therapeutic effect, at this time if you continue to use may increase the risk of adverse reactions, so once the expiration date of the insulin are not recommended to use. In addition, expired insulin can not play a good effect of lowering glucose, if patients use expired insulin treatment for a long time will also lead to poor glycemic control, and may even induce acute complications such as ketoacidosis or chronic complications such as diabetic nephropathy and retinopathy. Patients who need to use insulin therapy should use it under the guidance of a doctor to ensure that it is used within the expiration date of the insulin, and should not be used once the expiration date has expired.