Cold Weather + Type 1 Diabetes

Cold weather doesn’t just mean bundling up before you head outside. If you live with type 1 diabetes (T1D), it can change how your body behaves in ways that are easy to miss until you know what to look for. It may even play a role in how T1D starts in the first place!

When you’re managing T1D 24/7, 365 days per year, colder months bring their own curveballs that you can forget about until winter rolls back around. You may find your insulin is more sensitive to temperature, or your devices glitch more than usual in the cold. The shift from summer to winter blood sugar levels can feel jarring, especially when fall is usually way too short!

While you may not be ready to navigate the cold, this guide explains how to approach it comfortably and safely, and even how it may play a part in some people’s diagnosis stories.

Does cold weather affect T1D diagnosis?

While the exact cause of T1D is still unknown, researchers believe T1D can start when a genetic predisposition meets an outside trigger. A virus is one of the leading suspects! Recent research reviewing the evidence on viral infections and T1D found that a virus can damage the very cells that make insulin—sometimes by attacking them directly, other times by tricking the immune system into attacking them by mistake. When the body attacks itself like this, it’s called an autoimmune response.

Viruses also tend to spread more easily when it’s cold, which may help explain why T1D diagnoses climb in colder climates. Finland has one of the highest rates of childhood T1D in the world. Scientists are still trying to figure out why cold climates and T1D cases seem to happen together. It’s an observed pattern, but the reason isn’t known yet. Research is still ongoing.

Dealing with the cold and T1D day-to-day

Once you’re diagnosed, cold weather adds a new variable to blood sugar math. Some people run high. Others run low. Honestly, it can flip week to week, or even day to day, because cold weather isn’t the only factor at play!

You still need to consider factors like stress, what you’re eating, your menstrual cycle (if you’re female) and your activity levels, in addition to temperature. The most reliable way to know how cold affects your body specifically is to check your blood sugar more often than usual when temperatures drop.

There’s a real physiological reason behind the chaos, and it starts in your body. Cold stresses your body, so it releases stress hormones like cortisol to give you a burst of energy. These hormones can make your body less sensitive to insulin, which tends to spike blood sugar. Shivering, on the other hand, burns energy and lowers it. Bulky winter clothes make it easier to miss the usual warning signs of a low. And dry indoor heat quietly dehydrates you, which matters more than people realize, since dehydration on its own can spike your blood sugar. 

Put it all together and you’ve got a lot of moving parts to track!

Here are some proactive ways to manage your T1D in the cold:

• Check your blood sugar before you head outside: especially before anything active like skiing, sledding or shoveling snow. Check more often than usual when you’re outside.
  
• Bring snacks and water: you can get dehydrated in winter too, from dry air or a hard workout in the cold.
  
• Dress in layers: that way, you can adjust as your body warms up or cools down. It’s always better to have something to remove than to wish you’d brought warmer clothing.
  
• Stay active: regular movement in winter still helps your blood sugar and your mood. People with T1D can still enjoy activities like skiing and snowboarding.

How to protect your insulin and diabetes devices in the cold

The cold doesn’t just mess with your body. It can mess with your diabetes supplies, too. Frozen insulin stops working even after it thaws, so if you suspect a vial or pen froze, throw it out and start a fresh one—don’t risk it. When you’re outside, carry insulin close to your body or in an insulated case, not in a cold car or an outer coat pocket, since both can drop below freezing without you ever noticing.

A few specific numbers are worth knowing, and worth double-checking against your own supplies (Dexcom, for instance, publishes exact storage ranges for its sensors, transmitters and receivers):

• Insulin freezes at 32 degrees Fahrenheit, or 0 degrees Celsius.
• Store unopened insulin in the fridge, between 36 and 46 degrees Fahrenheit (2 to 8 degrees Celsius).
• Once you open a vial or pen, most insulin lasts about 28 to 30 days at room temperature. Check your specific label, since this can vary by brand.
• Most pumps, CGMs and blood glucose meters (BGMs) only work correctly above about 40 degrees Fahrenheit, or 4 degrees Celsius. Check your device’s manual for its exact range.

Keep devices and test strips in an inside pocket, close to your body, so your body heat keeps them warm. A device that gets too cold might throw an error, give you a wrong reading or just shut off—let it warm back up before you trust anything it tells you. Hand warmers can help, but don’t let them touch the device directly; too much heat damages it, same as too much cold. 

It’s also worth asking your diabetes care team about a backup plan. Think about carrying extra test strips and a backup way to take insulin in case something taps out on you in the field.

Take care of yourself throughout the winter season

Shorter, darker days can drag down your mood and energy, and that alone makes T1D harder to manage—the motivation to test, cook, plan and move takes a hit right along with everything else.  Sleep, stress management, staying active and good hygiene, like regular handwashing, matter just as much in January as they do in June. 

The Centers for Disease Control’s (CDC) cold-weather guidance points to a few key stressors that affect most people at this time of year: 

• Flu season
• Unpredictable holiday routines
• Less daylight

While winter surely has its downs, there is still a lot to look forward to. Don’t hibernate until the spring! With a few precautions—most of them just common sense once you know the numbers—you can still get outside and move your body, enjoying the season.

And if the isolation side of winter is hitting harder than the cold, you don’t have to sit with it alone. Beyond Type 1’s Community Apps connect you with other people living with T1D who genuinely get what these months are like. Join our apps to ask questions, vent for a minute or just not feel like the only one checking your blood sugar in a parking lot before you go sledding.