Key takeaways
Heat can cause dehydration, which can make it harder for people with diabetes to manage their blood sugar levels.
Staying hydrated, avoiding the peak hours of heat and sun, and closely monitoring your blood sugar levels can help you avoid dips or spikes.
Heat can also take a toll on diabetes medications and supplies, so take extra care to keep them out of the heat and sun, too.
During the summer, hot weather and high humidity can make it harder to keep your blood sugar levels under control. Extreme heat changes insulin absorption, increases the risk of dehydration, and even degrades essential medical supplies. Understanding these physiological shifts and optimizing insulin heat storage tips will help you keep your diabetes medications summer heat safe and maintain stable blood sugar levels. Here are diabetes summer tips for managing diabetes during the summer months.
How does heat affect diabetes and blood sugar?
When it’s hot outside, your body’s sweat glands kick in to help you cool down. Sweating accomplishes this task, but your body also loses fluids when you sweat. You can become dehydrated if you aren’t diligent enough about replacing those fluids. If you become dehydrated, blood glucose can become concentrated, causing your blood glucose levels to spike.
Shriya Gandhi, MD, an endocrinologist with UI Health in Chicago, Illinois, calls it “a vicious cycle.” High blood sugar levels also make you urinate more, making your body lose even more fluids, further exacerbating dehydration, according to the Centers for Disease Control and Prevention (CDC).
Does hot weather affect Type 1 and Type 2 diabetes differently?
High temperatures affect people with Type 1 diabetes a little differently than those with Type 2 diabetes, according to Dr. Gandhi. The main reason? Insulin use. While all people with Type 1 diabetes must take insulin, not everyone with Type 2 diabetes uses insulin. Insulin users are at higher risk of hypoglycemia (low blood sugar levels), which heat can worsen.
“When it’s really hot, your blood vessels get a little bit bigger, or dilate, to help your body cool off and release some heat,” Dr. Gandhi says. However, dilated blood vessels cause your body to absorb insulin at a faster rate, placing you at higher risk for low blood sugar, she explains. In other words, speeding up insulin absorption increases the risk of hypoglycemia.
Individuals with type 1 diabetes also have an increased risk of developing diabetic ketoacidosis (DKA) due to dehydration or illness,” adds Disha Narang, MD, endocrinologist and director of obesity medicine for Endeavor Health in Illinois. DKA is a life-threatening emergency caused by a severe lack of insulin, which causes the body to break down fat for energy, producing high levels of acidic substances (ketones) in the blood. Symptoms include fruity-scented breath, vomiting, and confusion and occur quickly. People with Type 1 diabetes tend to be at greater risk of DKA, but it can occur in people with Type 2 diabetes, too, according to the CDC.
Additionally, diabetes complications like diabetic neuropathy, or nerve damage, can make people with diabetes more vulnerable to heat. Damage to the blood vessels or nerves can affect your body’s ability to sweat effectively. This can make it hard to cool down, which can lead to heat-related illnesses.
“The key takeaway is that both groups can be affected,” says Anila Bindal, MD, an endocrinologist in Chicago, Illinois, and medical director at Abbott Diabetes Care. Monitoring glucose closely, especially with a continuous glucose monitor (CGM) can help you stay safe, she adds.
Other medications can make you more vulnerable to heat intolerance, so consult your healthcare provider to determine if any of the medications you take can increase your sensitivity to heat-related illness. For example, some antidepressants and high blood pressure medications can make you more sensitive to the heat.
Warning signs of heat-related illness to watch for in diabetics
Everyone should be familiar with the early warning signs of heat-related illness and dehydration, but people with diabetes should be especially vigilant about self-monitoring.
Signs of heat exhaustion can include:
- Cramps
- Pale, moist skin
- Headache
- Nausea and vomiting
- Diarrhea
- Weakness or feeling faint
- Fatigue
- Fever, or a temperature above 100.4 degrees Fahrenheit.
If not addressed, heat exhaustion can get worse and progress into heat stroke, which is a medical emergency.
“Symptoms of low and high glucose can feel similar to heat illness,” says Dr. Bindal. “Low glucose may cause sweating, dizziness, fatigue, and confusion. High glucose and dehydration can lead to increased thirst and feeling unwell, and in more serious cases, can increase the risk of diabetic complications like DKA.”
A good rule of thumb is to check blood glucose levels more frequently when outside in the heat. If you have diabetes and experience these symptoms, check your glucose and ketone levels right away, suggests Dr. Bindal.
Staying hydrated and summer-friendly foods for diabetes
Because hot weather can lead to dehydration, people with diabetes should be extra careful about staying hydrated.
“High blood sugar can cause an increase in urination, which can be even more dehydrating when added to heat,” explains Gillian Goddard, MD, an endocrinologist and nutritionist in New York City, and adjunct assistant professor of medicine at the NYU Grossman School of Medicine.
Maintaining good hydration, however, can help you stabilize your blood sugar levels. Focus on hydrating throughout the day and increasing your fluid intake when spending time outside or exercising. Your best bet? Drink plenty of water and limit sugar-sweetened beverages and alcoholic drinks (which can exacerbate dehydration), and use electrolyte replacements as needed.
In addition to drinking more water, eating water-rich foods, such as celery, grapes, cucumbers and peaches, can help you stay hydrated.
Exercising and staying active outdoors
Physical activity is a major component of staying healthy–and that advice applies to people with diabetes. In the summer, monitor the heat index, which tells you how hot it feels outside. According to the National Weather Service, the heat index can shoot up by as much as 15 degrees in direct sunlight.
“People with diabetes can still exercise in the heat,” Dr. Bindal says, but it’s best to develop an exercise plan with a healthcare professional. Avoiding strenuous outdoor activities when it’s hot outside is also key. Peak hours tend to be between about 10 a.m. and 4 p.m., so plan your outdoor walks, runs, bike rides, hikes, and other activities before or after that window. Or, move your activities indoors to take advantage of air conditioning, Dr. Gandhi recommends.
Note: Sunburn can also increase the risk of dehydration. If spending time outside during the day, apply plenty of sunscreen–and reapply as directed.
Another tip: check your blood glucose levels before, during, and after activity. Dr. Goddard cautions that it’s especially important for people who use insulin, as even moderate intensity exercise can lower blood sugar.
“A CGM can help track changes in real time, and for some people, the optional alarms [provide] peace of mind,” Dr. Bindal says. “Wearing lightweight clothing and taking breaks in the shade may also help prevent overheating.”
How to protect diabetes meds and supplies in the heat
The heat doesn’t just take a toll on your body. It can compromise diabetes medications and supplies. For example, test strips may not give an accurate reading if they’ve degraded from the heat. Extreme heat can also damage insulin pumps, which might cause malfunctions, and sweat can loosen adhesives on sensors. The bottom line? Avoid extreme temperatures when storing blood glucose meters, test strips, and other supplies.
Insulin must be kept in the refrigerator until opened for use, although once opened, you can safely keep insulin at room temperature for about 28-30 days. After that, you should discard it and use a new vial. It’s also important to keep it out of the sunlight. Sunlight and heat can cause insulin to break down so that it becomes less effective. A temperature over 86 degrees Fahrenheit places insulin at risk for damage.
Follow these tips to protect your diabetes medications and supplies from the heat:
- Keep diabetes supplies, insulin, or other medications out of direct sunlight.
- Don’t leave any diabetes meds or supplies in a hot car.
- Put your insulin and other heat-sensitive supplies in an insulated cooler bag with gel packs when traveling or heading outdoors.
- Don’t put insulin directly on ice or freeze it.
Keep an eye on your insulin to make sure it’s still safe to use. If you notice unexpected cloudiness, any clumps or particles, or a bad smell, it’s time to throw it out.
Diabetes supplies and how heat affects them |
||
|---|---|---|
| Supply/Medication | Heat risk | How to protect it |
| Insulin | Can break down and no longer effectively help with blood glucose management | Keep it refrigerated until opened, but do not put it directly on ice |
| Test strips | Can degrade and no longer give accurate readings | Keep out of direct sunlight and avoid extreme temperatures |
What summer diabetes supplies cost and how to save
When preparing for summer, keep track of all your supplies so you’ll have enough. For example, pack twice as many supplies as you think you’ll need when traveling. That way, you’re prepared in case something goes wrong or stops working.
It can be costly to stock up, but there are ways to reduce costs. Medicare has a $35 monthly cap on insulin for Medicare recipients. Using a SingleCare coupon can also help you save money on the additional costs of diabetes supplies and medications. You can also consult our insulin prices guide to learn more about prices and options.
- Managing diabetes in the heat, Centers for Disease Control and Prevention (2024)
- A guide to summer with T1D, Breakthrough T1D (2026)
- Diabetic ketoacidosis, Centers for Disease Control and Prevention (2024)
- Heat-related illnesses, Johns Hopkins Medicine
- Staying hydrated when you have diabetes, University of Maryland Health Hub (2025)
- Effects of extreme heat on diabetes, UMass Chan Medical School (2025)
- Using food to stay hydrated, Harvard Health Publishing (2024)
- What is the heat index, National Weather Service
- A reusable cap for disposable insulin pens protects insulin against temperature-induced degradation, Diabetes (2018)
- Insulin storage and preparedness, Michigan State University (2020)
- A guide to summer with T1D, Breakthrough T1D (2026)
Featured experts:
- Anila Bindal, MD, an endocrinologist in Chicago, Illinois, and medical director for Abbott Diabetes Care.
- Shriya Gandhi, MD, an endocrinologist with UI Health in Chicago, Illinois.
- Gillian Goddard, MD, an endocrinologist and nutritionist in New York City, and adjunct assistant professor of medicine at the NYU Grossman School of Medicine.
- Disha Narang, MD, an endocrinologist and director of obesity medicine for Endeavor Health in Illinois.
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