Storage of insulins before and after you open the vials or cartridges is very important.
Unopened insulins are best kept in the refrigerator. This provides a constant temperature and they can be kept until the manufacturer's expiration date shown on the vial or pen.
If unopened vials or pens are stored at room temperature, they can be kept for only more limited periods of time. At all times, the manufacturer's instructions should be studied and followed.
Opened insulins are best stored in the refrigerator to provide a constant temperature.
Whether refrigerated or not, opened vials are only good for 28 days.
Once opened, whether stored in the refrigerator or at room temperature, pens or cartridges in use are only good for the limited period of time stated in the manufacturer's instructions.