Unopened insulin needs to be refrigerated, and a suitable storage temperature for insulin is 2-8°C. For opened vials of insulin, insulin refills can be stored for up to 30 days at normal room temperature, usually this room temperature refers to around 20°C and no more than 25-30°C, which is long enough for the vast majority of patients to safely use up a full vial or stick of insulin. Refrigeration is not recommended for insulin that is being used because room temperature makes insulin products more stable, easier to mix, and more comfortable to inject, and repeated temperature changes can affect the effectiveness of insulin. However, the recommended storage temperature for unopened insulin is 2-8°C. In this environment, the biological activity of insulin can be maintained for 2-3 years.