Insulin needles for injection can, in principle, only be used once. Insulin preparations are usually injected subcutaneously or intravenously, and are mainly suitable for patients with type 2 diabetes who have type 1 diabetes, various acute and chronic complications, and poor glycemic control by diet, exercise, and medication alone. Diabetic patients should be careful to sterilize the injection site before injection, change the injection site frequently, and ensure that the needle is changed every time. In addition, insulin injection may cause some adverse reactions, such as hypoglycemia, allergic reactions, subcutaneous fat atrophy or hyperplasia at the injection site, edema and other symptoms. It is contraindicated for people who are allergic to any of the excipients of insulin preparations or during hypoglycemic episodes. Insulin needs to be carried out under the guidance of a doctor, if the above adverse reactions occur, go to the hospital in time to avoid delay.