Managing Diabetes in the Heat: What You Need to Know

But by knowing the risks, symptoms of a heat-related illness, and smart strategies for safe diabetes management in the heat, it’s entirely possible to enjoy the warmer weather while maintaining blood sugar levels.

Heat and humidity can pose unique challenges for people with diabetes, especially when combined with underlying complications.

Diabetes can “interfere with your body's ability to stay cool," says Ben Tzeel, RD, CDCES, a nutritionist in Tampa, Florida, and the founder of Your Diabetes Insider. "This can make it harder to regulate temperature and hydration in hot weather, which has direct effects on blood glucose levels."

Hot weather acts like a magnifier for blood sugar swings. “If you’re already a little high or low, the heat can push it further out of range faster than usual,” Tzeel says.

• Reduced ability to sweat: Nerve damage, or neuropathy, can impair sweat glands, making it harder for your body to cool down naturally.
• Sunburn and stress: A painful sunburn is more than skin deep. It can cause your body to release stress hormones, which may spike blood sugar levels.
• Dehydration: People with diabetes may become dehydrated faster. As fluid levels drop, blood glucose becomes more concentrated and can rise.
• Confusing symptoms: Fatigue, dizziness, and nausea can be symptoms of dehydration, hypoglycemia, hyperglycemia, or heat exhaustion. This makes it difficult to pinpoint the issue. “It’s not always easy to tell if you're dizzy because you're dehydrated or because your blood sugar is dropping,” says Tzeel. “That’s why checking your blood sugar frequently in the heat is so important. It removes the guesswork.”

High temperatures can also degrade or interfere with insulin, test strips, continuous glucose monitors (CGMs), and insulin pumps, leading to inaccurate readings and less effective treatment.

"Planning ahead is key when managing diabetes in the summer," says Tzeel. "Start with hydration, sun safety, and making sure your devices are protected from the heat."

• Avoid peak sun hours. In many areas, this is between the hours of 10 a.m. and 3 p.m. Opt for early morning or evening activities to avoid the worst of the heat.
• Stay hydrated. Carry a water bottle with you at all times. Sip consistently throughout the day. Aim for water or electrolyte drinks and avoid alcohol or sugary beverages. “If you’re sweating a lot, consider an electrolyte replacement without added sugar,” says Tzeel.
• Dress for the weather. Wear loose-fitting, breathable clothing and light colors to reflect sunlight. A wide-brimmed hat can provide extra protection.
• Use sunscreen. A broad-spectrum SPF 30 or higher can help prevent burns that could trigger stress-related blood sugar spikes.

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• Monitor blood sugar frequently. Check levels more often than usual, especially before and after outdoor activities. Apps and smartwatches can be useful reminders for this.
• Have snacks on hand. In the case of low blood sugar, always carry fast-acting carbs like glucose tablets or juice.

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• Don’t exercise in extreme heat. Opt for indoor workouts or water-based activities when temperatures soar.

“In a person with diabetes, there are more concerns beyond blood sugar levels,” explains Aimée José, RN, CDCES, a diabetes coach based in the San Diego area. “There are two reasons, really. The first is neuropathy, which affects their ability to sweat. And the second is when blood sugar levels rise, it can truly compound the effects of dehydration. It’s significantly harder for the body to cool itself down.”

• Heavy sweating
• Weakness or fatigue
• Dizziness or lightheadedness
• Nausea or vomiting
• Rapid pulse
• Headache
• Cool, clammy skin despite the heat
• Muscle cramps

If you or someone you know is experiencing these symptoms, seek shade, drink hydrating fluids, and cool the body with damp cloths or cold packs. Symptoms of heat exhaustion can mimic those of low blood sugar, so it’s important to check blood sugar levels and, if low, eat a snack to bring them back into target range.

José says signs and symptoms of heat exhaustion or a heatstroke in a person with diabetes should be treated as an emergency and warrants a trip to the emergency department. “Don’t wait, because heat exhaustion can easily lead to other dangerous issues, like diabetic ketoacidosis [DKA].”

Extreme temperatures can degrade the quality of these medications and devices. Insulin, in particular, is highly sensitive to heat.

“It doesn’t take much to destroy the quality of insulin in the heat,” says José. “Even just one hour in a very hot car or in the sun on the beach can do the trick. There are a variety of companies that sell products to protect your insulin from extreme temperatures. Or grab an ice pack and keep it in your purse with your insulin!”

• Keep insulin cool but not frozen. Store in a cooler with a cold pack, but make sure the insulin doesn’t come into direct contact with the ice.
• Use temperature-controlled cases. Some specialty cases use evaporation to keep insulin cool without refrigeration.
• Don’t leave supplies in a hot car. Even in a few minutes, the inside of a car can reach unsafe temperatures. Also, avoid storing medication or devices in direct sunlight or in the glove box of a car, which can still be very hot, even on days when the temperature is mild.
• Check expiration dates. Heat exposure can reduce the lifespan of insulin and test strips, so inspect regularly.
• Monitor device performance. If your CGM or pump starts acting up, heat exposure may be the culprit.

• Hot weather can increase the risk of both high and low blood sugar because of dehydration, medication sensitivity, and equipment malfunction.
• Be alert for signs of heat exhaustion, especially if you have existing diabetes complications.
• Stay hydrated, protect your skin, and check blood sugar more often to stay safe when the temperatures and humidity levels are high.
• Proper storage of insulin and devices is essential for accuracy and effectiveness.