How Continuous Glucose Monitors (CGMs) Can Make Exercise Easier When You Have Diabetes


Whether you are walking the dog or competing in a marathon, exercise becomes more challenging if you have diabetes. The development of continuous glucose monitors (CGMs), however, has made it easier than ever before to control blood-sugar levels while exercising.

Let’s examine how CGMs make exercising easier when you have diabetes.

What Are the Basics of CGMs?

CGMs are small devices typically worn on the arm or stomach that continuously track blood-sugar levels.

Most CGMs consist of:

  • A sensor—which is under the skin
  • A transmitter—which is above the skin and
  • The receiver—which is usually a smartphone or an insulin pump.

CGMs measure the amount of sugar in the interstitial fluid of your body fat, and then that information is sent to a receiver so you are aware of your blood-sugar levels in real time.

The data also shows arrows, which indicate if your blood-sugar levels are going up, down, or staying the same.

This is invaluable information to have when it comes to diabetes management, but especially when exercising.

What are the Exercise Benefits of CGMs?

Below are some of the benefits CGMs bring to your exercise.

Your doctor or Certified Care and Education Specialist can better discuss these benefits to you.

Optimized Performance

  • Having access to data helps athletes understand how exercise impacts their blood-sugar levels.
  • By tracking these patterns, athletes can adjust their diet and exercise routines to maintain optimal blood-sugar levels
  • This helps enhance performance and allows them to make informed decisions about how their blood-sugar levels are affected by the kind of exercise they do.

Provides Alerts for Hypoglycemia and Hyperglycemia

  • Sudden drops in blood sugar (hypoglycemia) or spikes in blood sugar (hyperglycemia) can severely impact an athlete’s performance and overall health.
  • CGMs provide alerts for these conditions, allowing timely interventions to stabilize blood-sugar levels.

Helps to Personalize Nutrition

Fede Fontana, who has a PhD in exercise physiology and is the co-founder of Enhance-d. According to Fontana, one of the most crucial strategies for regulating your blood-sugar levels in relation to exercise is nutrition.

“Depending on what you’re going to do, intensity-wise and duration-wise, you need to know how much sugar you need to consume around your exercise,” says Fontana. “These are adjustments you would make by looking at your CGM data and by knowing how intense the activity is and how long you’ll exercise for.”

Other variables you can try when it comes to nutrition include:

  • Testing different diet plans
  • Determining how the combination of carbs, fats and protein impacts blood-sugar levels
  • Exercising at different times after meals (immediately, one hour later, etc)
  • Working out in the morning in a fasted state

Helps Aid in Recovery Management

  • Monitoring blood-sugar levels post-exercise is crucial for recovery.
  • CGMs help athletes ensure their blood-sugar levels return to normal, aiding in effective recovery and preparation for the next workout.

Where to Have Your Blood-Sugar Levels When Exercising

According to Fontana, most people prefer to begin exercising when their blood-sugar levels are within—or slightly above—their ideal range.

Fontana advises beginning when your blood sugar is at a safe level and attempting to maintain it there by eating carbohydrates while working out.

In order to make sure their CGMs were accurate, Fontana requires athletes with whom she works to check their blood-sugar levels using a blood-glucose meter.

Make sure you discuss with your physician the appropriate blood-sugar values for your exercise.

CGM Integration with Technology

CGMs such as the Dexcom G7 are able to be integrated into various insulin pumps, including the Tandem t:slim X2 insulin pump as well as the Apple Watch.

This allows people with diabetes to

  • Enjoy more time in range
  • Be aware of hypoglycemia up to 20 minutes before it happens and
  • Create custom settings based on insulin needs.

The Dexcom G7 also pairs with health apps like eddii, Happy Bob, SNAQ, Sugarmate and Glooko.

The Role of CGMs in Competitive Sports

CGMs are not banned in most sports—especially when it is medically necessary, such as for athletes with diabetes.

These athletes can typically obtain a therapeutic use exemption to use CGMs during competition. This ensures they can manage their condition safely while competing.

However, athletes should stay updated about any changes in regulations by their sport’s governing body.

Other Tips for Athletes Using CGMs

Proper Placement of the Sensor

  • Ensure the CGM sensor is correctly placed as per the manufacturer’s instructions.
  • Proper placement ensures accurate readings and comfort during activities.

Calibrate Your Device

  • Some CGMs require periodic calibration with a standard blood glucose meter.
  • Ensure you follow the calibration schedule to maintain accuracy.

Monitor Trends, Not Just Numbers

While real-time blood-sugar readings are valuable, focusing on trends and patterns over time provides a clearer picture of how your body responds to various stimuli.

Integrate CGM Data with Other Metrics

  • Combine CGM data with other performance metrics such as heart rate, sleep patterns, and workout intensity.
  • This approach helps in making more informed decisions regarding training and nutrition.

Stay Hydrated

  • Dehydration can affect blood-sugar readings.
  • Ensure you stay well-hydrated, especially during intense workouts, to maintain accurate CGM readings.

Talk to Your Doctor About What Works

Regular consultation with healthcare professionals, including nutritionists and endocrinologists, can help interpret CGM data effectively and make necessary adjustments to your regimen.

This content was made possible by Dexcom, an active partner of Beyond Type 2.

Beyond Type 2 maintains editorial control over its content.

WRITTEN BY Kourtney Johnson, POSTED 06/26/24, UPDATED 06/26/24

Kourtney is a registered dietitian living with type 1 diabetes. She was inspired to study nutrition after learning about the role food plays in managing this condition. When she's not writing about all things food and diabetes-related, she enjoys reading, cooking, traveling, going to the beach and spending time with loved ones.