Insulin needles are recommended to be changed once and not reused. Insulin injection needles are disposable items, it is incorrect to use one needle for many days, reuse needles are easy to clog, contaminate, blunt and easy to break. 1. Needle clogging: there will be residual liquid in the reusable needle, which will affect the next injection dose, and the residual liquid will clog the needle if it stays for too long. 2. Needle easily contaminated: repeated use of the needle may make the needle is contaminated, easy to cause infection of the injection site when injecting again. 3. Needle easy to become blunt or even broken: repeated use of the needle will make the needle become unsharp, increasing the patient’s sense of pain. The needle will even become bent, increasing the probability of needle breakage. Therefore, it is recommended that diabetic patients inject insulin with needles one at a time to avoid causing damage. Diabetic patients should have regular hospital reviews to monitor their blood glucose and adjust the dosage of medication in a timely manner under the guidance of the doctor.