Ask The Expert
Insulin

It's no wonder you have questions about this, because the recommendations have changed over the years. Many years ago, insulin was not very stable, so it had to be refrigerated to preserve its potency. Over the years, insulin has changed and has become more pure and stable. So here are the facts:

• Insulin maintains potency longer if kept in the refrigerator. Unopened insulin bottles should always be stored in the refrigerator, and in this condition, insulin is good until its expiration date.
  
• Never store insulin in the freezer, or in direct sunlight or in the glove compartment, or in temperatures over 86 degrees F (30 degrees C). I used to remind my patients to "treat insulin like your pet-never leave it alone in a hot car!"
  
• Extreme temperatures and excess agitation should be avoided as they can cause insulin to lose potency, clump, "frost" (particles cling to the side of the vial which gives the vial a frosted appearance) or precipitate. Do not use insulin that has frosting, particles, or clumps.
  
• It is less painful (and usually not painful at all) to inject insulin that is at room temperature.
  
• For convenience and comfort, most people prefer storing their current bottle of insulin at room temperature. Insulin manufacturers' guidelines state that insulin may be stored at room temperature if used within 28 days-but this can vary, so be sure to read the package insert on the specific insulin you are using.
• Note that insulin pens have different recommendations, depending on the type of insulin. You can read more about that in the resource links below.