Check storage guidelines specific to your
insulin formulation [vile, pen, or cartridge] found usually on the product
package insert. If you do not have the insert Google make and type for temperature ranges. Going below or above the specified ranges will lower the insulin's efficacy and, in most cases, render it useless.
3. Also look closely for the printed expiration date on the vile/pen/cartridge. It is not a good idea to inject outdated medication. If in doubt toss it.