Exercise
Glucose Monitoring
Tracking Glucose during Exercise
Continuous Glucose Monitoring (CGM) can help you plan your meals or snacks before exercising. They can also help you spot high and low glucose levels during exercise. Below, we share some tips on how to use CGM during physical activity:
Tips for Sensor Use During Exercise
CGM and fingerstick glucose tests can show different readings during rapid changes in glucose (like during exercise).
- There can be a 15-30 minute delay between CGM and fingerstick readings during rapid glucose changes (up or down). Zaharieva DP, Turksoy K, McGaugh SM, et al. Lag time remains with newer real-time continuous glucose monitoring technology during aerobic exercise in adults living with type 1 diabetes. Diabetes Technol Ther 2019;21(6):313-321, doi:10.1089/dia.2018.0364 Li A, Riddell MC, Potashner D, et al. Time Lag and Accuracy of Continuous Glucose Monitoring During High Intensity Interval Training in Adults with Type 1 Diabetes. Diabetes Technol Ther 2019;21(5):286-294, doi:10.1089/dia.2018.0387 Guillot FH, Jacobs PG, Wilson LM, et al. Accuracy of the Dexcom G6 Glucose Sensor during Aerobic, Resistance, and Interval Exercise in Adults with Type 1 Diabetes. Biosensors (Basel) 2020;10(10), doi:10.3390/bios10100138 Fokkert M, van Dijk PR, Edens MA, et al. Performance of the Eversense versus the Free Style Libre Flash glucose monitor during exercise and normal daily activities in subjects with type 1 diabetes mellitus. BMJ Open Diabetes Res Care 2020;8(1), doi:10.1136/bmjdrc-2020-001193 Da Prato G, Pasquini S, Rinaldi E, et al. Accuracy of CGM Systems During Continuous and Interval Exercise in Adults with Type 1 Diabetes. J Diabetes Sci Technol 2022;16(6):1436-1443, doi:10.1177/19322968211023522
When in doubt, check with a fingerstick glucose meter!
- Especially if you don't trust the CGM number or trend arrow.
Avoid calibrating your CGM during exercise or when your glucose is changing quickly.
- It's better to calibrate when your glucose level is stable, with flat trend arrows, not after a big meal or exercise.
- Example: First thing in the morning is a good time to calibrate if needed.
- Wait about 20-30 minutes after exercise to let the CGM and fingerstick readings match up.
Check out our Wisdom section to learn more about glucose monitoring and exercise:
I chose to use a CGM and pump because they create a discreet combination that works well.
Mark
Even though my pump has malfunctioned before it is worth having because my blood sugar is more in control when I use it.
Ashley
It's worth it to me, particularly when I sleep and wake up to see that the closed loop has gotten my blood sugar down, or suspended my insulin.