No, you can't freeze insulin! Insulin is a temperature-sensitive medication; many questions have been asked about what happens when it's exposed to extreme temperatures such as severe cold or heath. Sadly, people rarely bother about what to expect should their insulin freeze.


It's necessary to note that a frozen insulin medication is as ineffective as one exposed to extremely hot temperatures. So you must always be mindful of where and how you store opened and unopened insulin.

That said, some important questions I will be answering in this Diabetic & Me article include;

  • Does insulin need to be refrigerated?
  • What happens if insulin is not refrigerated?
  • Can I use frozen insulin?
  • How can I tell if my insulin is spoiled?
  • How do I store insulin?
  • How to prevent your insulin from freezing?

Does Insulin Need to Be Refrigerated?

Top U.S. insulin drug manufacturers recommend storing unopened insulin in a refrigerator at approximately 36°F to 46°F. This storage condition must be met for the insulin product to maintain its potency until the expiration date on the package. Never store your insulin in a freezer or other freezing places.

You can store/use unopened and opened inulin vials or cartridges unrefrigerated for 28 days, provided you keep them at temperatures ranging from 59°F to 86°F.

What Happens if Insulin is Not Refrigerated?

Although insulin (open or unpen) can stay unrefrigerated at room temperature for up to 28 days, unopened insulin loses some of its properties, capacities, and potency when exposed to high temperatures, usually above 36°F to 46°F (2-8°C).

The effectiveness of your insulin continues to decrease the longer it is stored under such a temperature, ultimately resulting in its inability to stay potent until the expiration date printed on the insulin box.

Injecting damaged or expired insulin can make it harder to control your blood sugar levels, putting you at a higher risk of diabetes-related complications, including hyperglycemia, nerve damage, kidney damage, eye damage, and skin and mouth conditions.

Can You Use Frozen Insulin?

No, freezing insulin is not advisable! Throw frozen insulin into the trash and get a new vial or pen reservoir.

The top three drug manufacturers in the US producing insulin clearly state that any insulin stored below 2°C (36°F) will freeze. Frozen insulin can't pass through the needle and can't be injected in its frozen state. Even when they thaw, they can't regulate your blood sugars because the freezing temperature has already impaired the protein.

To ensure your insulin is safe, make sure it's protected from icy cold weather, such as during snowboarding. If you must store your insulin vial or pen in a fridge, keep it closer to the door, where it is less likely to get frozen, or better still, get an insulin cooler.

What Are Top Manufacturers Saying About Frozen Insulin?

It's always necessary to check out the manufacturer's instructions before taking any insulin injection. Here are the recommendations by renowned insulin manufacturers on what to do with frozen insulin:

Humulin

You will find this instruction on the package: "Storing the Humulin R U-500 vial: Do not use if it has been frozen." Products like Humalog, Levemir, Novorapid, Toujeo, Apidra, Tresiba, etc., warn against frozen insulin.

Novolog

The manufacturer's instruction: "Unused NovoLog® should be stored in a refrigerator between 2° and 8°C (36° to 46°F). Do not store in the freezer or directly adjacent to the refrigerator cooling element. Do not freeze NovoLog® and do not use NovoLog® if it has been frozen."

Lantus

The manufacturer's recommended storage conditions: "Do not allow Lantus to freeze. Do not put Lantus in a freezer or next to a freezer pack. If you see frost or ice crystals in your Lantus solution, throw it away."

How Can I Tell if My Insulin is Spoiled?

The most common way to identify damaged insulin is if you notice a change in its color or overall appearance. If, for instance, your clear insulin suddenly becomes cloudy or discolored, or has particles or crystals, then it's probably spoiled.

Insulin types and changes indicating they are damaged:

  • Lispro, Aspart, and Glargine: These are bright-colored insulin products, so if you observe any color change, cloudiness, or floating particles, it could be a sign of contamination or a damaged product.
  • NPH (Neutral Protamine Hagedorn): This type of insulin is naturally cloudy; however, if you find a tiny white clump at the bottom of the bottle or a "frosting" appearance on the inside wall of the glass vial, throw away or return to the seller, manufacturer, or distributor.

How Do I Identify Frozen Insulin?

Frozen insulin, just like any frozen liquid, becomes solid and opaquer, meaning that you can't possibly inject it.

It's a bit trickier to identify frozen but thawed insulin. This is because the thawing process returns icy insulin to a liquid state.

If you suspect your insulin might have frozen initially but is now in liquid form, scrutinize it for changes in colors and textures.

How to Store Insulin

Most cases of damaged insulin are usually due to poor storage. And as far as insulin storage is concerned, "too hot" or "too cold" is not an option.

The proper way to store your insulin meds depends on the brand or type. For instance, an insulin vial's storage recommendation differs from an insulin pen, and that of a vial or pen is not the same as that of an insulin pump.

Insulin vials

You can store unopened insulin vials in the fridge until their expiration date. Most opened insulin vials last up to 28 days with or without refrigeration. However, some products last more than 28 days outside the fridge. Examples are Human insulin (Humulin N), Insulin detemir (Levemir), and Insulin Degludec (Tresiba).

Insulin pump

The instructions for using or storing insulin pumps may differ from what is written on the box. So, if you use a pump, always read its storage instructions. If the instructions on the pump and box are different, follow the stricter instruction requiring the shortest number of days for a change of insulin.

The standard recommendations for pump storage:

  • Insulin Lispro (Humalog) — 7 days.
  • Insulin Aspart (NovoLog) — 7 days
  • Insulin Aspart (Fiasp) 6 days
  • Insulin Glulisine (Apidra) 48 hours

Insulin pens

You can refrigerate your unopened insulin pens to keep them safe until their expiry dates. However, unlike insulin vials, you must not store your pens in a fridge once they are open.

The best condition is to keep them at room temperature, remove the needles to prevent contamination, and cover them with caps to protect them from light.

For pens, most open and unopened insulin stored outside the fridge will stay effective for 28 days if you stick to the conditions above.

Other products (open or unopen) may stay less or more than 28 days at room temperature. Examples are:

  • Humulin N Kwikpen — 14 days.
  • Insulin detemir (Levemir FlexTouch) — 42 days.
  • Insulin degludec (Tresiba FlexTouch) — 56 days.

Insulin mixes

Insulin mixes are pre-mixtures of different insulins, mainly containing 70–75% intermediate-acting insulin and about 25–30% rapid or short-acting insulin. Unopened insulin mix vials and pens can be refrigerated until their expiry date.

Most opened insulin mix vials can be stored inside the fridge or at room temperature for 28 days. Examples are Insulin Lispro 75/25 and 50/50 (Humalog 75/25 and Humalog Mix 50/50) and Insulin Aspart 70/30 (NovoLog Mix 70/30). Although Humulin 70/30 can last up to 31 days.

Open mixed insulin pens must not be refrigerated. Once opened, some can last for 10 days at room temperature — an example is Insulin Lispro Pen (Humalog Mix 75/25 and Humalog Mix 50/50). Others can stay up to 14 days at room temperature — an example is Insulin Aspart Pen 70/30 (NovoLog Mix 70/30)

How to Prevent Your Insulin From Freezing

Many people with diabetes find it more challenging to keep insulin safe during winter than in summer. For instance, you can guarantee your insulin's safety if you put it inside a portable medical fridge — even under the scorching summer sun. But the same can not be said about an accidental power outage during winter with no means to warm your room. You may find it hard to stop your insulin meds from freezing in such situations!

So, how do you protect your insulin from cold weather?

  • Don't expose your insulin to the cold weather outside during winter.
  • Don't forget your insulin supplies in the car overnight when temperatures outside are freezing.
  • Use the right fridge compartment to store insulin in your home fridge during summer. Or better yet, use an insulin cooler or a portable medical fridge for the best result.
  • Do not put your insulin in a freezer.
  • Always keep your insulin close to your body if you are outside hiking or snowboarding in freezing winter weather. I recommend using your inside pockets or keeping the insulin vial, pen, or pump in direct contact with your skin.
  • Always go for insulin coolers with anti-freezing properties. I like the 4AllFamily insulin coolers with biogel ice packs. Since biogel freezes at 2°C and insulin freezes at 0°C, your insulin won't freeze, even if it's in steady contact with the frozen biogel pack.

Conclusion

When temperatures are out of control, chances are your blood sugar will follow suit. Hot or cold weather extremes can affect your diabetes medications and injectables, making it difficult to control sugar levels and prevent diabetes complications.

A 2018 study indicated a sharp rise in hospitalizations among diabetic people when temperatures hit extreme high or low (during summer and winter). Hence, to keep your blood sugar under control, it's pertinent to know the storage recommendations for your insulin meds and stick to them.

About the Author

Ely Fornoville

Hi, I'm Ely Fornoville and I am the founder of Diabetic & Me. Being a type 1 diabetic since 1996 I developed a passion to help people learn more about diabetes. I write about diabetes and share stories from other diabetics around the world. I am currently using a Medtronic Guardian 4 and a Minimed 780G insulin pump with Humalog.

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