Frozen insulin is usually not reusable. Because the structure of insulin is composed of two peptide chains, and a variety of amino acids constitute these two peptide chains, which then form insulin, the biological nature of insulin determines that after freezing, it will lead to the denaturation of peptides and amino acids, and the biological effect will disappear, and it will not be able to play a role in lowering blood sugar. Therefore, if insulin is frozen and then thawed, it should not be used again even if it becomes liquid. Insulin can be kept in the freezer at a temperature of 2°C to 8°C. Be careful not to stick to the wall, as sticking to the wall of the freezer can cause insulin to freeze and cause insulin denaturation. Try not to put it on the refrigerator door, as it will easily cause the insulin to shake and affect the quality of insulin. For insulin that is normally used, it can usually be stored indoors if the room temperature is within 20°C. Insulin being used is usually recommended to be used within 1 month, and if it is not used, it is recommended to discard the rest. When applying insulin, it is also important to note that there are many types of insulin, and different types are suitable for different patients’ conditions and need to be applied under the guidance of a doctor. In addition, it is also necessary to strengthen the monitoring of blood glucose during the use of insulin. If insulin is denatured and has no biological effect, the blood glucose level will be found to rise when tested after the use of the drug, especially frozen insulin. Of course, it is a relatively common phenomenon for insulin to cause low blood glucose if it is applied in the process. When low blood glucose level is found, it should be corrected by eating sugary foods in time, and at the same time, under the guidance of a doctor, appropriate dosage and regimen adjustment should be made to the insulin currently used.