Family enjoying a warm summer day.

The CGM Blog

10 Tips for Managing Diabetes in Hot Weather
Hot weather and humidity can impact your blood sugar levels. Here’s a few things you should know to beat the heat while
If you’re planning to enjoy summertime fun or headed for a sunny vacation destination, getting the most out of warmer temperatures takes a little extra consideration when you live with diabetes. There are many factors that have an impact on your blood sugar levels, and hot weather is one of them. Heat affects the way all of our bodies function. It can cause more obvious bodily responses like sweating, but it also influences things we can’t see on the surface, like our metabolism—the way that our bodies use food for energy. This means that it can cause changes in your blood sugar levels that you might not expect.
There are some important things that you need to be aware of if you’re planning to spend time in hot temperatures, especially if you want to get active. It’s a good idea to talk to your doctor and diabetes care team about adjusting your diabetes management plan during the warmer months or when you’re going on a trip to a balmy climate. Learning more about why and how heat impacts glucose levels can help you take steps to care for yourself and fully enjoy your time in the sun.
How Heat Affects Blood Sugar
Hot and humid weather directly influences glucose levels. This is because the metabolism is responsible for both blood sugar management and temperature regulation in the body.3 It controls how fast carbohydrates are digested and turned into glucose to be absorbed into the bloodstream. It also mediates the release of insulin, which is the hormone that allows our cells to use glucose for fuel.4
When the body heats up, it increases insulin sensitivity which causes more glucose to be absorbed into the cells at a faster rate.2, This can lead to low blood sugar or hypoglycemia.2 Studies have shown that an individual’s A1C tends to be lower during the summer months, partly because it’s often much warmer in the summer and people are typically outside enjoying warm weather.1,5
Wuick Definition - Insulin Sensitivity - Insulin is a hormone that helps your muscle, fat, and liver cells absorb glucose in your blood. Insulin sensitivity refers to how receptive those cells are to insulin. Greater insulin sensitivity means the body has an easier time absorbing glucose to use for energy. Low insulin sensitivity is known as insulin resistance.
Heat also causes blood to flow from the center of the body out to the extremities to help cool it down. However, in individuals living with diabetes, this process may not happen as efficiently as it does in those who do not live with the condition. For individuals who live with diabetes complications such as nerve or blood vessel damage, the body’s signals to sweat and cool down the body may not be as responsive.7 This can lead to getting overheated, which may further lead to glucose control issues.5
Individuals living with diabetes can become dehydrated faster as well.7 Losing fluid through sweat, particularly if you are exercising, can be an issue as less water in the body means a higher concentration of glucose in the blood.7 When blood sugar levels rise, the body will trigger urination to get rid of the extra glucose. This can worsen dehydration.7
Heat also changes the way your body responds to your insulin injections. While heat around an insulin injection site may increase insulin absorption, dehydration reduces the blood supply to the skin.5, This can be an issue when you’re injecting insulin because there won’t be as much blood available at the injection site to carry it to the rest of your body.7 Additionally, insulin needs to be stored between 2ºC and 8ºC. Diabetes Canada recommends that insulin that’s exposed to temperatures over 30ºC should be thrown out. Heat-damaged insulin may be cloudy, grainy, or turn a brownish colour. If you’re unsure whether your insulin has been damaged, talk to your doctor or pharmacist.
Even if it’s not very hot out, humidity may make it more difficult for the body to maintain a balanced temperature. It’s harder for sweat to evaporate in humid conditions, which means that the body can’t cool down as quickly.7 Keep humidity in mind if you’re exercising or breaking a sweat during activity, as it can make it much more challenging to maintain your body temperature.7
Remember, It’s Not Just About the Heat
Most Canadians know that hot weather means a change of pace. It’s important to remember that shifts in your daily routine can impact your diabetes management as well. Summertime might mean the kids are out of school or that you’re more active outside the house than you are in the winter. Likewise, when you’re on vacation somewhere hot, you’re probably not on your usual schedule (and you deserve it!) or may have switched time zones. This can also disrupt your regular diabetes management habits. Be aware of how the weather influences your routine, and speak to your doctor about potentially adapting your diabetes management plan to suit any heat-related lifestyle changes.
You may also eat differently during summer or while on vacation in a warmer climate. Whether it’s popsicles on the back deck or a plate of pasta in Rome, it’s important to continue to make choices in line with your diabetes diet plan. Alcohol and sugary drinks might be on the menu, but water is the best hot-weather drink for those living with diabetes.11
Good weather may also get you excited about exercise and fun physical activities like swimming, golfing, hiking, cycling, or simply playing at the park with your pets or building sand castles at the beach with the kids. You might be doing chores outside, like mowing the lawn or gardening, which can be as strenuous as a workout. Activities like these can increase sweating and, in turn, the chance of dehydration.7,12
Woman using a hand-fan to deal with the heat.
Tips for Managing Your Blood Sugar when it’s Hot Outside
Having fun in the sun has wonderful benefits that shouldn’t be overlooked. Getting active outside in a sunny environment has been shown to boost overall mental health.13 Additionally, getting more vitamin D (which is created by the body when exposed to sunlight) has been linked to decreased insulin resistance in individuals living with type 2 diabetes (T2D).14
There are steps you can take to make sure that you get all the benefits of hot weather without compromising your diabetes management plan. Here are just a few tips to help you beat the heat:
  1. Drink plenty of water. If you’re planning to exercise, Diabetes Canada recommends drinking fluids 30 minutes before exercise and then drinking 250 ml every 20 minutes. After exercising, be sure to drink until you’ve more than quenched your thirst.12
  2. Avoid alcohol and drinks with caffeine, which can increase urination and dehydration.12
  3. Check your glucose levels before, during, and after you’re active.7
  4. Choose light-coloured, loose-fitting, lightweight clothing.7
  5. If you’ve experienced nerve damage to your feet, avoid going barefoot and wear moisture-wicking socks along with shoes that fit well.
  6. Remember to wear and reapply sunscreen, and put on a hat when outside.7
  7. Exercise indoors with air conditioning if it’s really hot and humid outside.12
  8. Do outdoor chores or activities in the early morning before the day is at its hottest.12
  9. Be sure to head for shade or go indoors every 15 minutes.12
  10. Store your insulin or other medications in a cooler and avoid exposure to direct sunlight.7
Keep an Eye on Your Glucose while You Enjoy the Sun
Enjoying good weather is about being in the moment and having fun with your loved ones. With continuous glucose monitoring (CGM) technology like Dexcom CGM Systems, you can keep an eye on your glucose levels from the palm of your hand without the need for routine fingersticks.*
The Dexcom CGM System consists of a wearable, water-resistant device that takes glucose readings from a small sensor inserted just below the skin and sends the data to a receiver or compatible smart device every five minutes. It can be worn while swimming and sweating so you can see where your glucose levels are at during your favourite warm-weather activities.
Learn how Dexcom CGM Systems can help you take control of your diabetes management so that you can focus on soaking up the sunshine.
Read more
*If your glucose alerts and readings from the G6 do not match symptoms or expectations, use a blood glucose meter to make diabetes treatment decision
  1. Pallubinsky H, et al. Passive exposure to heat improves glucose metabolism in overweight humans. Acta Physiol (Oxf). 2020;229(4):e13488. doi:10.1111/apha.13488
  2. Hot Weather and Diabetes – Staying Safe in the Heat. Diabetes.co.uk. Updated Reviewed January 25, 2023. https://www.diabetes.co.uk/diabetes-and-hot-weather.html
  3. Metabolism. Cleveland Clinic. Updated August 30, 2021. https://my.clevelandclinic.org/health/body/21893-metabolism
  4. Hantzidiamantis PJ, et. al. Physiology, Glucose. StatPearls Publishing. Updated September 20, 2021. Accessed May 15, 2022. https://www.ncbi.nlm.nih.gov/books/NBK545201/
  5. Kenny GP, et. al. Body temperature regulation in diabetes. Temperature. 2016;3(1):119-145. doi:10.1080/23328940.2015.1131506
  6. Understanding Insulin Resistance. American Diabetes Association. Accessed June 15, 2023. https://diabetes.org/healthy-living/medication-treatments/insulin-resistance
  7. Managing Diabetes in the Heat. Centers for Disease Control and Prevention. Updated July 27, 2022. https://www.cdc.gov/diabetes/library/features/manage-diabetes-heat.html
  8. How to Manage Your Diabetes in Extreme Summer Heat. Cleveland Clinic. Updated July 21, 2020. https://health.clevelandclinic.org/how-to-manage-your-diabetes-in-extreme-summer-heat/
  9. Getting started with insulin. Diabetes Canada. May 2022. https://guidelines.diabetes.ca/docs/patient-resources/getting-started-with-insulin-injections.pdf
  10. Diabetes and hot weather. Diabetes UK. Accessed May 29, 2023. https://www.diabetes.org.uk/guide-to-diabetes/managing-your-diabetes/hot-weather
  11. Healthy eating. Diabetes Canada. Accessed May 31, 2023. https://www.diabetes.ca/nutrition---fitness/healthy-eating
  12. Exercise safely in the summer heat. Diabetes Canada. July 12, 2022. https://www.diabetes.ca/about-diabetes/stories/exercise-safely-in-the-summer-heat
  13. Taniguchi K, et al. Influence of External Natural Environment Including Sunshine Exposure on Public Mental Health: A Systematic Review. Psychiatry International. 2022; 3(1):91-113. doi:10.3390/psychiatryint3010008
  14. Low Vitamin D May Contribute to Insulin Resistance. American Diabetes Association. Accessed May 31, 2023. https://diabetes.org/healthy-living/recipes-nutrition/vitamins-diabetes/low-vitamin-d-insulin-resistance
  15. Nerve damage & amputation. Diabetes Canada. May 31, 2023. https://www.diabetes.ca/resources/tools---resources/nerve-damage---amputation

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