Insulin and Hot Weather: 10 Things You Need to Know

Insulin is a protein, and because of its chemical structure, it is easily "spoiled" if left in the heat. Per the American Diabetes Association, it is best to keep your insulin at a temperature between 36°F to 46°F. (Never freeze insulin as it will lose its effectiveness.) 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. (Some research suggests that insulin can last up to 42 days after opening.) Using insulin that has broken down due to time or temperature may result in higher blood sugar levels because your usual dose doesn’t contain its usual strength and efficacy.

Unopened insulin typically has an expiration date of one year from the time of purchase. If you aren't using it immediately, be careful not to 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 on the cusp of being too cold, so be careful!) And always double-check the setting when you store insulin temporarily in a friend’s fridge or at a hotel. Per the American Diabetes Association, insulin contained in the infusion set of an insulin pump device (e.g., reservoir, tubing, catheters) should be discarded after 48 hours, and discarded immediately if the infusion set of a pump device is exposed to temperatures over 98.6°F.

It may be hot outside, but your insulin is fine at room temperature for about 28 days, after which it will start to degrade and lose its potency. 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. Even if you are storing the insulin in your fridge, consider leaving it out at room temperature prior to an injection: The ADA recommends injecting insulin at room temperature because it is less painful than when it's cold. It's not just the insulin you'll want to keep at room temp: Leaving your blood sugar monitor, insulin pump, and other diabetes equipment in the heat can damage them, so store them indoors as well.

Per the Centers for Disease Control and Prevention (CDC), storing insulin or other oral diabetes medications in direct sunlight or a hot car can cause them to lose their effectiveness. 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 could easily destroy a small vial of insulin worth hundreds of dollars. When you’re out and about, keep your insulin in a safe zipped-up kit that you carry in your purse or backpack.

Leaving your insulin in your beach bag on the hot sand, under the hot sun, can absolutely cook and destroy your medication. If you are carrying your insulin with you to the beach or pool, make sure to store your bag in the shade and keep it from coming in contact with a surface that is hot (sometimes that just means putting a towel beneath your bag and the sand). Consider packing several cold packs in your bag, or even bottles of ice water to prevent the temperature in your sack from rising too high.

If you live in a part of the country where 100°F is the norm throughout the summer, it is crucial to make sure your insulin pump is protected from the sun’s rays by putting it in your pocket. Even in milder summer temps, it's important to be sure your pump 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. At the same time, know that the way your body uses insulin changes in the heat, according to the CDC. That means you may need to test your blood sugar levels more often, and adjust your insulin doses accordingly during the summer months.

Looking for ways to protect your medication while you're on the go? 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. Some models last for up to 45 hours, or five times longer than traditional ice packs. In a pinch, packing your insulin between bottles of ice water will buy you several hours of safe storage as well.

While rising summer temps can make it tricky to transport insulin to the beach, airplane travel brings its own set of complications. Never put your insulin in a suitcase that is going to be checked and stored in the luggage section of the airplane. The luggage hold on planes is not temperature-controlled and it can be really hot or really cold in that compartment, meaning you may arrive at your destination with a batch of useless insulin. Better to be safe: Always keep all the insulin you’re traveling with in your carry-on.

The cold of winter can bring challenges of indoor heat. If you're new to taking insulin, you might not think about the potential hazards at a friend’s house or a hotel if you accidentally put your bag down in front or on top of a heating vent. In a short period of time, your insulin can be heated to temperatures that destroy its efficacy. The same is true for overheating your insulin by placing it in front of a heater in a car, near a fireplace, or even leaving your kit on top of the stove when the oven is preheating. Remember: The safest spot for your insulin is in the refrigerator.

How your body handles blood sugar can vary measurably when it's hot outside. Many things can cause a glucose spike, including extremely hot temps. Dehydration (from weather, illness, exercise, etc.) raises the concentration of sugar in your bloodstream because there’s simply less water in your blood to dilute it. This results in higher blood sugar levels and means you either need more insulin or you need to keep yourself better hydrated. Moreover, per the Cleveland Clinic, if your diabetes has damaged the nerves to your sweat glands, you may not be able to perspire as a way to cool yourself off. Keep an eye on how you're feeling in the heat, and seek out shade and AC if you start feeling confuse or weak.