Diabetes Forecast

Can Insulin Go Back in the Fridge?

After removing insulin glargine (Lantus) from the refrigerator for use, can it be refrigerated over and over again after having warmed to room temperature, or does this degrade it? Name Withheld

Roger P. Austin, MS, RPh, CDE, responds:

For you to get consistent, predictable results when using insulin, carefully follow the insulin manufacturer's recommended storage conditions.

What to Know:

Each vial of insulin or box of insulin pens comes with instructions about how to properly store that particular product. Be sure to read and follow these recommendations. As long as vials or pens are stored unopened in the refrigerator (at 36 to 46 degrees Fahrenheit), they are good until the expiration date on the container. Questions about the insulin's potency start when you open the vial or pen and begin to use it.

Find Out More:

Opened vials of the following insulins and mixtures are stable for 28 days either at room temperature (defined by manufacturers as 77 to 86 degrees) or in a refrigerator (36 to 46 degrees): insulin glargine (Lantus), insulin glulisine (Apidra), insulin aspart (NovoLog), insulin lispro (Humalog), Novolin-N, Humulin-N, Novolin-R, Humulin-R, and mixtures of insulin (Novolin 70/30, Humulin 70/30, NovoLog Mix 70/30, Humalog Mix 75/25, and Humalog Mix 50/50). Opened vials of insulin detemir (Levemir) are stable for up to 42 days at the recommended conditions. Insulin should not be allowed to freeze; if vials or pens are found to be frozen, they should be discarded and replaced with fresh supplies.


Shuttling opened insulin vials between refrigeration and room temperature does not appear to affect the insulin's potency under these conditions and time periods. However, manufacturers of insulin pens do not recommend storage in a refrigerator once a pen is opened and in use.

Protect insulin from exposure to light and extremes of temperature above and below those noted. Insulin should never be stored in a vehicle, or on windowsills or ledges, where it can be exposed to such conditions.

When traveling, keep insulin on your person or in your carry-on bag. Insulin placed in suitcases that are transported in cargo holds of aircraft, boats, and buses or in car trunks may be exposed to damaging temperature extremes.



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