Type 1 Diabetes and Cold Weather

Type 1 diabetes doesn’t hibernate. The winter and cold weather can complicate your type 1 diabetes management in several ways, from freezing insulin and affecting medical-device functionality to increasing your risk of infection.

With some extra planning, you can make sure your diabetes supplies stay safe, that you stay on top of blood sugar levels, and that you plan ahead for possible sick days.

Insulin can freeze when stored at 32 degrees F or colder, just like water, says Jovan Milosavljevic, MD, an assistant professor of medicine at Montefiore Einstein in New York.

“When this happens, its protein structure becomes damaged,” he says. “Even if the insulin later thaws, it won’t work the way it should.”

“To prevent freezing, never keep unopened insulin in the freezer or near the back wall of the refrigerator," says Hess-Fischl, adding that insulated bags are available to keep insulin at an appropriate temperature.

In the winter, you should be especially careful about how you carry your insulin. Leaving a vial or pen outdoors in a backpack, purse, or car could easily expose it to freezing temperatures. If you’re spending the day skiing or sledding or even just shopping, stay mindful of the insulin you keep on your person so that it doesn’t freeze.

“Keep insulin close to your body, like inside a jacket, and consider an insulated pouch when traveling or spending long periods outdoors so the temperature stays safely above about 40 degrees F,” Dr. Milosavljevic says.

If you use an insulin pump or a continuous glucose monitor (CGM), note that extreme cold can affect how they operate.

Take some precautions to ensure that devices also remain at an appropriate temperature.

“Wear them in areas [where] they are less likely to be directly exposed to the cold,” says Risa Wolf, MD, a pediatric endocrinologist and the director of the pediatric diabetes program at Johns Hopkins Children's Center in Baltimore.

Body heat also can help keep devices at a safe temperature, Hess-Fischl says.

It’s also possible for the cold to affect adhesives on pumps and CGMs.

“Adhesive can sometimes harden, losing stickiness as a result,” Hess-Fischl says. “The cold and lower humidity leads to dry skin. Dry skin can cause adhesives to become more abrasive to the skin by increasing their hold.”

Drinking more water might help them stick, she says.

If you customarily add additional adhesive tape to protect your pump or CGM, Hess-Fischl suggests finding an adhesive that releases gently, such as those that include zinc.

“Cold weather can cause the body to release stress hormones such as cortisol and adrenaline,” Milosavljevic says. “These hormones stimulate the liver to release extra glucose, which can raise blood sugar levels.”

If you are exposed to cold, your body also will try to preserve heat and limit blood flow to your skin, he says: “Insulin absorption may be decreased, which can lead to higher sugars as well.”

Poor circulation in cold hands also can make it harder to get a glucose reading from a fingerstick. This may lead to inaccurate readings and improper treatment.

“It’s a good idea to check your blood sugar frequently, since close monitoring is the best way to see how cold weather affects you and to respond to any trends,” Milosavljevic says.

Winter weather and winter habits also may lead to less exercise and a less healthy diet, especially during the holidays, making blood sugar harder to control.

“Decreased activity will increase insulin resistance, leading to higher glucose levels and the need for more insulin,” Hess-Fischl says.

Hess-Fischl recommends making an effort to take regular walks, be they outside or simply walking in place, and exercising on your own. Even housework can be productive physical activity, she says.

“Being closer to snacks and foods that may tempt you to eat more, gain a little bit of weight, and also increase the insulin needs,” Hess-Fischl says.

“Winter illnesses, such as the flu, can result in higher blood sugars because of the body's need for more insulin during illness,” Dr. Wolf says. “Illnesses can also increase the risk of ketone development and diabetic ketoacidosis in people with diabetes.”

“Make sure to follow your doctor's instructions during times of illness by checking ketones frequently and seeking medical guidance as needed,” Wolf says.

“Bring hypoglycemia treatment that is easy to carry and is not affected by temperatures, first and foremost,” Hess-Fischl says. “Juice and gels may not be the best idea.”

Keep those snacks close to your body while you are out in cold weather.

“Glucose tabs or gummies kept in an inside pocket would be ideal since they will not freeze as easily as liquids,” Hess-Fischl says.

• Managing type 1 diabetes during cold-weather months may require paying extra attention to the temperature of your insulin, medical devices, and hypoglycemia snacks.
• Insulin is unusable if it freezes, so be sure to keep it within the recommended temperature range, storing it in an insulated bag if necessary.
• Cold weather itself can activate stress hormones that can increase blood sugar levels and decrease insulin production, making regular blood sugar checks key.
• Have a sick-day plan in place if you get a winter illness such as the flu, RSV, or COVID-19, all of which may come with more severe symptoms and complications if you have type 1 diabetes.