While insulin is a life-saving medicine for people with diabetes, it's also a constraint. Maintaining correct insulin management and keeping up with injections several times a day require a lot of rigor and motivation.
On top of that, insulin is very sensitive to heat and light and must be stored accordingly. Surveys show that most diabetics don't store their insulin correctly. Unfortunately, bad storage conditions lead to insulin losing its potency and uncontrolled blood sugar.
So, how exactly should you store your insulin at home? When does it need to be refrigerated, and when does it not?
Learn everything you must know about insulin storage, refrigeration, transportation, and more.
What is insulin?
Insulin is a hormone used to treat type 1 and type 2 diabetes. It regulates the amount of glucose in the blood (also called blood sugar or glycemia). It’s produced by the islets of Langerhans cells in the pancreas.
People diagnosed with diabetes need insulin injections when their pancreas does not produce enough or no insulin. In that case, animal-derived or synthetic forms of insulin are prescribed.
There are two main types of insulin: fast-acting (bolus) insulin that acts on after-meals blood glucose, and long-acting (basal) insulin that keeps the levels within the range between meals and overnight.
Basal insulin is usually administered once or twice a day. Common brands of basal insulins sold in the U.S are NPH insulin (Humulin-N and Novolin-N), Lantus, Toujeo, and Basaglar (glargine insulin), as well as Levemir (detemir insulin), and Tresiba (degludec insulin – ultra long).
Bolus insulin is injected before, during, or after meals that contain carbohydrates or sugars. Common brands are NovoLog, Fiasp (aspart insulin), Humalog (lispro insulin), Apidra (glulisine insulin), as well as Novolin-R, and Humulin-R (regular insulin).
Whether fast-acting or long-acting, insulin is administered via manual subcutaneous injections or insulin pumps. It’s delivered in different containers, including vials, auto-injectable pens, or cartridges.
Does insulin need to be refrigerated?
All insulins must be refrigerated, irrespective of their types and containers. But let's zoom in to understand why and how you should refrigerate your insulin.
Why must insulin be refrigerated?
All manufacturers of insulin brands sold in the U.S. recommend that insulin is refrigerated. That’s because the hormone is highly sensitive to high temperatures and temperature fluctuations.
Insulin belongs to the class of biological drugs. They’re human-made proteins that contain parts of living organisms. As such, insulin is very sensitive to heat, temperature fluctuations, and light exposure. Room temperature breaks down the protein and destroys it.
So, just like a steak would go bad if unrefrigerated, insulin will too.
That’s why whether you’re using Lantus, Novolog, Humalog, Basaglar, or others, you must keep your insulin vials, pens, or cartridges in the refrigerator before first use.
At what temperatures must insulin be refrigerated?
Insulin isn't the only medicine that needs refrigeration. Other biologics used for diabetes, like Ozempic, Trulicity, or Victoza, and unstable drugs require refrigeration to stay active and effective.
But what does refrigeration mean? What temperatures are we referring to? If you’ve been prescribed insulin for your diabetes management, you must make sure your domestic fridge is set at the right temperature range and offers the best storage conditions.
The rule of thumb is that insulin must be refrigerated between 36°F and 46°F (2°C and 8°C). Be careful the temperature does not get below 36°F (2°C) because freezing could also deteriorate insulin.
We recommend that insulin-dependent patients check their domestic fridge temperature regularly. Some choose to use a connected thermometer that sends an alarm whenever the refrigerator temperature goes outside the desired range.
Related article: At what temperatures should you store refrigerated medications?
How long does insulin last in the fridge?
Unopened insulin adequately stored at fridge temperature lasts until the expiration date on the package. All insulin pens, vials, and cartridges have an official expiration date labeled by their manufacturer. It’s usually about one year after the purchase date but always double-check. If you can't find it, ask your pharmacist for help.
Past this expiration date, your insulin becomes unstable and unsuitable for use. Therefore, it's considered expired, even if it has never been opened and always kept in the fridge.
Expired insulin isn’t safe for use. It may have lost all or part of its effectiveness. Using it may lead to high blood sugar levels and severe health complications.
Bear in mind that insulin has two expiration dates: the one labeled on the container and the one that occurs after it's been opened or taken out of the fridge (see below!).
Related article: Does insulin expire?
Does insulin need to be refrigerated after opening?
No, insulin does not need to be refrigerated after opening. Once you’ve opened and punctured a vial or used a preloaded pen, you can keep it at room temperature.
You may re-refrigerate insulin after opening (if it's too warm inside your home, for example) but understand it won’t prolong its lifespan. Insulin that’s been opened or out of the fridge must be used within about a month (see below for more details).
Related article: How to store and refrigerate your Lantus pens and vials at home?
What happens if insulin is not refrigerated?
Insulin refrigeration is a rigorous requirement all insulin-dependent diabetics have to deal with. Fortunately, there's some room for maneuver here, as insulin does not go bad immediately if not refrigerated. Most of them can safely be left out of the fridge for about a month. So, let’s look deeper into what happens exactly when you leave your insulin unrefrigerated.
Does insulin go bad if not refrigerated?
Insulin can go bad if not refrigerated. Actually, insulin often goes bad. As said above, it's a very unstable medicine that heat can quickly deteriorate.
Laboratory and clinical tests have shown that most insulins are stable at room temperature for about a month (a little less for some and a little more for others). If insulin is left unrefrigerated for more than a month, it starts deteriorating, going bad, and losing potency.
Related article: Can insulin go bad and how to tell if it has?
Is it safe to use insulin that’s been out of the fridge for too long?
Insulin that has been out of the fridge for more than a month (average) is not safe for use anymore.
While it won’t poison you or make you sick, the manufacturer can’t guarantee its effectiveness. Simply put, using insulin that’s been out of the fridge for too long is like injecting water. It just does not work or deliver its full potential dose!
Unrefrigerated insulin that has gone bad or inefficient won’t lower your blood sugar. The main risk is hyperglycemia which could ultimately lead to diabetic ketoacidosis coma.
How to tell if insulin has gone bad?
The first thing that can indicate your insulin may be bad is time. We recommend always noting the opening date on your vials or pens of insulin, as well as the date you first took it out of the fridge (if they're not the same). About one month after that day, your insulin will start deteriorating. So you should stop using it and get a new one from the fridge.
Visual inspection can also help notice bad insulin. Most insulins are water-like, clear, colorless liquids. Therefore, any change of color, cloudiness, clumps, strings, or frost inside, can indicate your insulin has gone bad. However, note that some insulins, like isophane insulins (NPH, Insulatard, Humulin-N, and others) are normally cloudy.
Unusual high blood sugar or difficulty lowering your glycemia can also be a sign you’re using bad insulin. In any case, when in doubt, throw it out!
Related article: How long do insulin vials last, and how many do you need per month?
What to do with expired insulin?
There are three main scenarios where insulin expires: when its expiration date is passed, when it's been out of the fridge for more than a month, or when it's been exposed to temperatures over 77°F(25°C).
Whatever the reason, expired insulin should never be injected. Immediately dispose of vials, pens, or cartridges that are unsafe for use.
According to the U.S. Food and Drug Administration (FDA), expired insulin can be thrown into household trash. However, we recommend removing it from its original container (vials or cartridges) and mixing it with unpleasant substances to make it unattractive to children and pets.
Sharps like needles and syringes used for insulin injections must be disposed of in sharps containers.
Related article: Can you prefill insulin syringes? How long are they good for?
How long can insulin be out of the fridge?
While insulin must be refrigerated when not in use, it can be stored at room temperature for about a month once open or out of the fridge. However, leaving insulin unrefrigerated still requires some storage precautions, including protecting it from heat and keeping track of its expiration. So, let’s explore how long exactly you can leave your insulin out of the fridge and what you should do to protect it meanwhile.
How long can insulin be kept at room temperature?
As a rule of thumb, insulin can be kept at room temperature for about a month (see details below for each brand of insulin).
However, insulin that has been mixed, diluted, removed from its original container, or altered in any way, should be discarded within a maximum of two weeks if unrefrigerated.
By room temperature, we mean anything between 56°F and 80°F (13-26°C). It means that while you can keep your insulin out of the fridge for a while, you must still protect it from high heat and ensure it's never exposed to temperatures over 80°F (26°C).
Therefore, people living with insulin-dependent diabetes are recommended to use an insulin cooler when living in or traveling to places where the weather gets warm.
How long can insulin be unrefrigerated exactly?
As said above, the average time insulin can be unrefrigerated is one month. But there are slight variations depending on the type and brand of insulin you’ve been prescribed.
Here are examples of how long the most common brands of insulin can stay out of the fridge without deteriorating:
- Lantus can be unrefrigerated for up to 28 days
- Novolog can be unrefrigerated for up to 28 days
- Humalog can be unrefrigerated for up to 28 days
- Humulin can be unrefrigerated for up to 31 days
- Apidra can be unrefrigerated for up to 28 days
- Novolin N can be unrefrigerated for up to 42 days
- Levemir can be unrefrigerated for up to 42 days
- Tresiba can be unrefrigerated for up to 56 days
- Toujeo can be unrefrigerated for up to 42 days
- Basaglar can be unrefrigerated for up to 28 days
- Fiasp can be unrefrigerated for up to 28 days
Always check the storage instructions on the paper or ask your doctor or diabetes nurse if your particular insulin has a shorter or longer lifespan.
What if insulin gets warm?
Insulin can quickly deteriorate if it gets warm. Laboratory tests have shown that the peptide hormone loses effectiveness when exposed to extreme temperatures (above 80°F (26°C) or below 32°F (0°C)). Naturally, the longer the exposure, the more potency it loses.
Situations where insulin may get warm are more frequent than you’d think, and carelessness may happen to anyone. For example, your insulin isn't safe in the car on a sunny day nor placed near the stove or in your purse when the outside temperature is over 80°F (26°C).
Insulin that has gotten warm isn’t safe for use anymore. Injecting it can result in high blood glucose and severe health complications. So only use it in case of emergency and if you have no other choice, but always prefer getting a new vial or pen from your fridge or the nearest pharmacy.
Keep your USB Insulin Cooler Plugged-in For Optimal Refrigeration!
Related article: What to do if you run out of insulin?
How to store insulin properly?
We've seen the rules, and now let's focus on practical tips to store insulin in the most optimal conditions. Always remember that paying extra attention to your insulin is well worth the pain. It can keep it more efficient for longer, which has a direct impact on both your blood glucose and your finances!
Related article: How to mix two insulins in one syringe?
Store unopened insulin in the fridge
As seen above, unopened insulin must always be stored in the fridge. Keep all your vials, pens, and cartridges in your refrigerator as soon as you return from the pharmacy. Afterward, only take a vial or a pen out of the fridge when you need to use it.
Additionally, if your trip home from the pharmacy is longer than 30 minutes or the outside temperature is above 80°F (26°C), we recommend using a medical cooler or a cooler bag to ensure the cold chain isn’t disrupted.
Where to store insulin in the refrigerator?
There are a few more things that help ensure your insulin is stored in optimal conditions inside your fridge:
- The fridge temperature should be as stable as possible. Avoid fluctuations.
- Do not jam-pack your fridge so the air can circulate inside.
- Avoid keeping the door open for too long when taking something out of the fridge.
- Do not store the insulin near the freezer compartment as it risks freezing, which isn't good either.
- Keep your insulin vials, pens, or cartridge at the center of the fridge where the temperature is the most stable. Avoid placing it at the bottoms, sides, or door shelves.
- Check your refrigerator temperature often, or consider using a smart thermometer.
Store opened insulin at room temperature
Once you’ve taken an insulin container out of the fridge for first use, you can store it at room temperature. You do not have to put it back in the fridge. It must be used within about a month (see details for each brand of insulin above).
During that time out of the fridge, your insulin must be protected from high heat and never exposed to temperatures above 80°F (26°C).
Related article: What happens if you miss a dose of insulin?
Use an insulin cooler if you’re traveling
Because of its instability and rigorous storage instructions, traveling with insulin can be quite challenging.
People with diabetes living in or traveling to places with warm weather are firmly advised to use good medical-grade travel coolers.
The ones we offer at 4AllFamily have been specially designed for insulin and other refrigerated medicines. They’re highly reliable and can keep your stocks of opened insulin refrigerated and/or your in-use insulin cool and protected from the outside heat. We're the #1 recommended brand in the U.S. market.
Browse through our catalog of portable coolers for refrigerated medications!
Related article: How to keep insulin cold on a plane?
Protect insulin from light and breakage!
Exposure to sunlight and indoor light may also deteriorate your insulin. So, make sure to store it in dark places. If you're using insulin pens, keep the cap on.
Related article: Can hot weather affect blood sugar?
Last but not least, insulin vials are made of thin glass and are incredibly fragile! Therefore, we strongly recommend using a silicone vial protector to prevent any unfortunate accident if dropped on the floor!
Trusted Sources & References:
 Da Silva Xavier G. The Cells of the Islets of Langerhans. J Clin Med. 2018 Mar 12;7(3):54. doi: 10.3390/jcm7030054. PMID: 29534517; PMCID: PMC5867580.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5867580/#:~:text=Islets%20of%20Langerhans%20are%20islands,a%20means%20to%20treat%20diabetes.
 George K, Woollett G. Insulins as Drugs or Biologics in the USA: What Difference Does it Make and Why Does it Matter? BioDrugs. 2019 Oct;33(5):447-451. doi: 10.1007/s40259-019-00374-1. PMID: 31388968; PMCID: PMC6790337.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6790337/
 Heinemann L, Braune K, Carter A, Zayani A, Krämer LA. Insulin Storage: A Critical Reappraisal. J Diabetes Sci Technol. 2021 Jan;15(1):147-159. doi: 10.1177/1932296819900258. Epub 2020 Jan 29. PMID: 31994414; PMCID: PMC7783014.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7783014/