Unopened insulin is stored at a constant temperature between 2 and 8 degrees Celsius and will fail if above 10 degrees Celsius or below 0 degrees Celsius. Opened insulin is stored at room temperature below 25 degrees and will fail if above 28 degrees or after exposure to the sun. Insulin is mainly used to lower blood sugar and treat diabetes. When injecting short-acting and mixed insulin, diabetic patients must eat meals on time to prevent hypoglycemia. Attention is also paid to regular monitoring of blood glucose and adjusting the dose of insulin at any time. The side effects of insulin are mainly hypoglycemic reaction, subcutaneous fat atrophy, subcutaneous hard nodules and allergic reactions, such as subcutaneous rash, itching, and even breathing difficulties, chest tightness and breathlessness, etc. Failed insulin cannot be injected.