Insulin and Hot Weather: 10 Things You Need to Know

by Ginger Vieira Health Writer & Patient Advocate

Insulin is considered the most powerful hormone in the body — but it’s also quite sensitive to bright lights and extreme temperatures, especially the kind of insulin that’s man-made in a lab, not by your pancreas. Knowing how to prevent your insulin from getting too hot during day-to-day activity is a must if your day-to-day life depends on each dose. Here’s what you need to know:

woman holding insulin
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Insulin Is a Protein, and It Can Wery Easily “Spoil” Under the Wrong Temperature Conditions

Insulin prefers to be kept between 36° to 46°F. When an insulin vial or pen is opened, it will retain its potency to help you manage your blood sugar for up to 28 days before it starts to break down. Using insulin that has broken down due to time or temperature results in higher blood sugars because your usual dose doesn’t contain its usual strength and efficacy.

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All Unopened Insulin Should Be Kept in the Refrigerator

It typically has an expiration date of 1 year from the date of purchase. But don’t store your insulin in the back of the fridge (where it’s often colder), and be sure your fridge is at a normal setting of 35°F to 40°F. (35 °F is just on the cusp of being too cold, so be careful!) And double-check the setting when you store insulin temporarily in a friend’s fridge or at a hotel.

Insulin Is Safe at Room Temperature, After It’s Been Opened, for About a Month

Insulin is fine at room temperature but will start to degrade and lose its potency after 28 days. Ideally, if you don’t use enough insulin to use up a vial within a month, then you can ask for insulin pens which contain less insulin, and you can draw from it to get insulin into your pump, or if you prefer syringes over pen-needles. The ADA recommends injecting insulin at room temperature. It is less painful.

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Don’t Leave Insulin in Your Car—Ever!

The inside of a car can easily be 20 degrees hotter when it’s closed up while you’re at work or getting groceries. Leaving your insulin in the car for more than a few minutes during any time of year is risky and could easily destroy a small vial of insulin worth hundreds of dollars. When you’re out and about, at work — wherever — keep your insulin in a safe zipped-up kit and keep it in your purse or backpack.

At the Beach or Other Summertime Outings

Leaving your insulin in your bag on the hot sand, under the hot sun, can absolutely cook and destroy your insulin. At the very least, make sure the bag containing your insulin is in the shade and is on a surface that isn’t naturally warm (sometimes that just means putting a towel beneath your bag and the sand).

Young diabetic woman holding an insulin pump in the city
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What About Wearing Your Insulin Pump in Extremely Hot Weather?

If you live out west where 100 °F are the norm throughout the summer, this is crucial — and you’ll want to make sure it’s protected from the sun’s rays by putting it in your pocket. Even in milder summer temps, be sure it isn’t up against your own skin. When you’re on a bike ride, for example, your direct and rising body heat could easily cook it.

woman using insulin outside with carrying case
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There Are Some Very Simple Products to Help Protect Your Insulin

The “Frio Pack” is one of the simplest and most affordable storage products to keep your insulin cool in hot environments. The basic model costs $22.99, and requires zero refrigeration. Instead, it’s a unique technology that is activated by immersing the pack in water for a few minutes. Give it a quick towel-dry, put your insulin inside, and off you go. You can reactivate it as often as you need to.

People walking through airport with luggage.
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Be Careful When Traveling by Plane

Never, never, never put your insulin in a suitcase that is going to be checked and stored in the luggage section of the airplane. It can be really hot or really cold in that part of the plane, and you’ll arrive at your destination with a batch of useless insulin. Always keep all the insulin you’re traveling with in your carry-on.

Space heater on pine floor.
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Even During the Winter, Be Wary of Heat

If you visit a friend’s house and accidentally put your bag down right in front of a heating vent, your insulin might get cooked and destroyed during your visit. The same goes for when you’re in a car, or even leaving your kit on top of the stove when the oven is preheating. Just be aware, always, that your insulin is in a safe spot.

Woman extremely sweaty from workout.
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Last on the Subject of Hot Weather

The insulin that has already been injected into your body needs to be considered when you’re in extremely hot temps, too. Dehydration (from weather, illness, exercise, etc.) raises the concentration of sugar in your bloodstream because there’s simply less water in your blood, too. This results in high blood sugar levels, and means you either need more insulin or you need to keep yourself more hydrated...likely both! Water, water, water!

Ginger Vieira
Meet Our Writer
Ginger Vieira

Ginger Vieira has lived with Type 1 diabetes and Celiac disease since 1999, and fibromyalgia since 2014. She is the author of Pregnancy with Type 1 Diabetes, Dealing with Diabetes Burnout, Emotional Eating with Diabetes, and Your Diabetes Science Experiment. Ginger contributes regularly for Diabetes Strong, Healthline, HealthCentral, DiabetesDaily, EverydayHealth, and her YouTube channel. Her background includes a B.S. in professional writing, certifications in cognitive coaching, Ashtanga yoga, and personal training, with several records in drug-free powerlifting. She lives in Vermont with her husband, their two daughters, and their dog, Pedro.