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Glucose Monitoring

Tracking Glucose during Exercise

Continuous Glucose Monitors (CGMs) can help you figure out the timing of before-exercise meals or snacks. They can also help you catch high and low blood sugars during exercise. Below we provide some information on how to utilize CGMs during your physical activity: 

Tips for Sensor Use During Exercise

CGM (sensor) and fingerstick blood glucose can have an increased lag time during rapid changes in glucose (for example: during exercise)

  • You can sometimes see around a 15-30-minute delay between CGM and fingerstick blood glucose during rapid changes (up or down) in blood glucose

When in doubt, fingerstick blood glucose measurement using a glucose meter is important!

  • Particularly if you don’t trust the sensor reading

Generally, consider avoiding calibrations during exercise/activity or rapid changes in glucose

  • Better to calibrate when glucose level is stable, flat trend arrows, not after a large meal or exercise
  • Example: First thing in morning is generally good time to calibrate, if needed
  • Can generally wait around 20-30 minutes after activity to see if CGM and fingerstick glucose had time to “catch up” to one another


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