Insulin is a hormone that helps regulate blood sugar levels. It is an essential medication for people with diabetes. Insulin must be kept at proper temperatures to maintain its potency and effectiveness. High temperatures can cause insulin to degrade faster, potentially reducing its blood sugar lowering abilities. Proper insulin storage is key to making sure insulin stays effective for use.
Quick Answer
Yes, insulin can go bad if it gets too hot. Insulin should be stored according to the manufacturer’s instructions, which is often in a refrigerator between 36°F – 46°F (2°C – 8°C). Exposing insulin to high temperatures above 86°F (30°C) for any length of time can cause it to degrade and lose effectiveness faster.
How Insulin Works
Insulin is produced by the pancreas and helps regulate the amount of sugar (glucose) in the bloodstream. It allows cells throughout the body to uptake and use glucose for energy. People with diabetes either don’t produce enough insulin (type 1 diabetes) or can’t properly use the insulin they make (type 2 diabetes). This causes high blood sugar levels. Insulin injections or infusions are used to manage diabetes by replacing or supplementing the body’s own insulin production.
Insulin works by binding to receptors on cells throughout the body, signaling them to absorb glucose from the bloodstream. The glucose can then be used as an energy source. Different types of insulin are available, classified by how quickly they start working (onset) and how long their effects last (duration). Faster acting insulin helps manage blood sugar spikes after meals, while longer acting forms provide a baseline insulin level through the day and night.
Why Heat Damages Insulin
Insulin consists of proteins that are sensitive to temperatures. Heat can cause insulin proteins to change shape and break down over time. This process is known as protein denaturation. Once insulin proteins are denatured, they are unable to properly bind to receptors and allow glucose uptake.
High temperatures also increase the rate of chemical reactions within insulin, causing it to degrade faster. This can reduce insulin potency even before visible changes occur. Damaged insulin may have little to no effect in lowering blood sugars as intended.
Temperatures That Damage Insulin
According to the manufacturers, insulin should be stored at 36°F – 46°F (2°C – 8°C) and not be frozen. Temperatures below freezing can also damage insulin. Room temperature is generally considered between 68°F – 77°F (20°C – 25°C).
Here are some temperature guidelines for insulin:
- Below 36°F (2°C): Can cause insulin to freeze and form crystals. Crystallized insulin will not work properly.
- 36°F – 46°F (2°C – 8°C): Recommended refrigerator storage temperature.
- 59°F – 86°F (15°C – 30°C): Insulin may be stable for a few weeks, depending on type. Avoid prolonged heat exposure.
- Above 86°F (30°C): Can damage insulin, increasing the risk of reduced potency or effectiveness.
The hotter the temperature, the faster insulin degrades. Leaving insulin in direct sunlight, near heat sources like stoves, or inside hot vehicles can expose insulin to damaging heat.
How to Tell if Insulin Has Been Damaged from Heat
It’s not always easy to tell if insulin has lost some of its effectiveness, especially before use. Here are some signs that insulin may have been overheated:
- Color change – Properly stored insulin should appear clear and colorless. Overheated insulin may turn cloudy or brown.
- Clumping – Heat can cause insulin proteins to stick together into clumps. You may notice clumps or particles floating in the insulin solution.
- Frosting on the insulin bottle – High temperatures can damage the protective coating around glass insulin bottles. This causes moisture accumulation and frosting.
- Difficulty mixing – Denatured insulin proteins don’t dissolve properly. You may have trouble reconstituting cloudy mixed insulin solutions.
- Reduced potency – Damaged insulin may not lower blood sugars as quickly or as effectively as expected.
Protecting Insulin from Heat
Keeping insulin properly stored can help prevent exposure to heat and maintain its effectiveness. Recommendations include:
- Storing unopened insulin in the refrigerator between 36°F – 46°F (2°C – 8°C).
- Not keeping insulin in the freezer or allowing it to freeze.
- Keeping opened insulin at room temperature below 86°F (30°C).
- Discarding any insulin that has been exposed to temperatures over 98.6°F (37°C).
- Not leaving insulin in hot vehicles or direct sunlight.
- Avoiding extremes of temperature by keeping insulin with you when traveling.
- Not using insulin that has changed appearance, such as clumping.
Insulin pumps and pens allow people with diabetes to carry insulin with them throughout the day. It’s important to protect insulin pumps or pens from getting overheated as well, such as avoiding direct sun exposure. If the insulin gets too hot, it may need to be replaced.
Traveling with Insulin
Traveling can make keeping insulin at proper temperatures more challenging. Here are some tips for travel:
- Use an insulated bag or cooler with ice or cold packs to keep insulin cool.
- Keep insulin with you in a carry-on bag when flying, rather than checking it through to the hold.
- Consider getting a prescription for an extra supply of insulin as backups in case any is damaged from temperature spikes.
- Avoid leaving insulin in hot vehicles for more than a few minutes.
- Check insulin’s appearance and test its effectiveness if there is any concern it got too hot.
How Long Does Insulin Last if Unrefrigerated?
The length of time insulin remains stable and usable depends on both the temperature and the type of insulin. General insulin storage guidelines are:
- Refrigerated insulin remains effective until the expiration date, up to about 28 days once opened.
- Unopened insulin vials or pens can be kept at room temperature below 86°F (30°C) for 28-56 days depending on type.
- Opened (in use) insulin may last 28-42 days unrefrigerated depending on type.
In hotter conditions, insulin degrades faster. Any temperature above 98.6°F (37°C) can rapidly damage insulin. Here are some time spans insulin can maintain its stability if left unrefrigerated in warm to hot temperatures:
- Up to 1 week at 68°F – 77°F (20°C – 25°C).
- Up to 1 month at 59°F – 68°F (15°C – 20°C).
- A few days at 77°F – 86°F (25°C – 30°C).
- A few hours at 86°F – 95°F (30°C – 35°C).
- Less than 1 hour at over 95°F (35°C).
Discard any insulin that has been exposed to direct sunlight or temperatures over 98.6°F (37°C), even for just a short period of time. Don’t use insulin that you suspect has lost potency from heat exposure.
Does Cooling Insulin Extend its Shelf Life?
Putting insulin in the refrigerator as recommended can help extend its shelf life by slowing chemical changes that cause it to degrade over time. However, cooling insulin that has already been exposed to heat for a prolonged period cannot reverse any damage already done. Denatured insulin proteins don’t regain their original shape and effectiveness when put back in the refrigerator.
Any insulin that shows signs of heat damage like clumping or cloudiness should be replaced rather than trying to cool it and reuse it. Never use insulin that you suspect has been compromised by heat exposure. Using a damaged insulin product can result in poor blood sugar control.
How to Store Insulin
Correct storage is vital for keeping insulin safe and effective as long as possible. General insulin storage recommendations include:
- Unopened vials and pens – Store in the refrigerator between 36-46°F (2-8°C). Can also keep unopened at room temperature below 86°F (30°C) for 28-56 days depending on type.
- Opened (In-use) vials – Can store for up to 28 days either refrigerated or at room temperature less than 86°F (30°C). Write the date opened on the bottle.
- In-use pens – Keep at room temperature below 86°F (30°C). Refrigeration is not needed. Follow manufacturer instructions for open pen storage times.
- Pre-filled pens – Store new, unopened pens in the refrigerator until first use. Once in use, keep at room temperature.
- Infusion pumps – Keep insulin reservoirs/cartridges refrigerated until use. Store the pump at room temperature with cartridge attached.
Proper storage helps insulin retain its potency and effectiveness as long as possible. However, no insulin should be used past the manufacturer’s expiration date.
It’s also important to take other precautions like:
- Not storing insulin in the freezer compartment of a refrigerator.
- Avoiding extreme temperature fluctuations.
- Protecting insulin from direct sunlight and heat sources.
- Not using insulin that has changed appearance or looks damaged.
Traveling with Insulin
Maintaining ideal insulin temperatures can be challenging when traveling. Some tips include:
- Use an insulated bag or cooler with ice/cool packs.
- Keep insulin in carry-on bags rather than checked luggage during air travel.
- Test blood sugar more often to check insulin effectiveness if temperatures cannot be controlled.
- Don’t leave insulin in hot vehicles for more than a few minutes.
- Have backup insulin available in case any gets too hot.
Discarding Used Insulin
Used insulin syringes, cartridges, and infusion sets must be disposed of safely to prevent needlestick injuries or improper reuse. Proper insulin disposal guidelines include:
- Never throw loose needles, syringes, lancets, or other “sharps” directly in the trash. Use an approved sharps disposal container.
- Many pharmacies offer sharps disposal programs or containers.
- Some communities have household hazardous waste collection programs that accept used sharps.
- Used insulin pens can be disposed of in a sharps container or sometimes in regular household trash if the needle is properly covered.
- Don’t attempt to remove, recap, or clip used insulin needle tips before disposal.
Ask your pharmacist or healthcare provider where sharps containers and insulin disposal options are available in your area. Proper insulin and syringe disposal helps protect the community.
The Takeaway
Insulin is a vital medication for people with diabetes that requires careful storage and handling. Exposure to excess heat can damage insulin, causing it to lose potency and effectiveness faster. Keeping insulin properly refrigerated or at moderate room temperatures is important to preserving drug stability and shelf life. Any insulin subjected to temperatures over 98.6°F (37°C), even briefly, should not be used and replaced immediately. With proper storage and care, insulin can safely be used to help manage diabetes.
Here are some key tips to remember:
- Store unopened insulin in a refrigerator between 36-46°F (2-8°C).
- In-use insulin can be kept at room temperature less than 86°F (30°C).
- Don’t expose insulin to hot vehicles, direct sunlight or temperatures above 98.6°F (37°C).
- Inspect insulin before use and discard if it has changed appearance or looks damaged.
- When traveling, use insulated cooling bags or keep insulin with you.
- Properly dispose of used insulin syringes, pens and needles in a sharps container.
Checking insulin before each use and taking measures to keep it in the manufacturer’s recommended temperature range can help ensure you receive the full benefits of your prescribed insulin.
