Question 1

Do I need to remove my Dexcom sensor for medical procedures?

Accepted Answer

MRIDo not wear any Dexcom CGM system during magnetic resonance imaging (MRI).The Dexcom CGM systems have not been tested during an MRI scan. The magnetic fields could damage the components of the Dexcom which may cause inaccurate sensor readings or prevent alerts.1,2,3DiathermyDo not wear any Dexcom CGM system during high frequency electrical heat (Diathermy) treatment.The Dexcom CGM systems have not been tested during a procedure involving diathermy. The heat generated could damage the components of the Dexcom CGM systems may cause inaccurate sensor readings or prevent alerts. 1,2,3X-ray, CT scan or radiation therapy – Dexcom G7 or Dexcom ONE+If you need an x-ray, CT scan, or radiation therapy while wearing the sensor, discuss these safeguards with your healthcare provider 1,2:Avoid including the sensor in the scanned area during the procedure.Cover the sensor with a lead apronCT Scan – Dexcom G6Do not wear your Dexcom CGM (sensor, transmitter, receiver, or smart device).31 Dexcom G7 User Guide, 20242 Dexcom ONE+ User Guide, 20253 Using your Dexcom G6, 2023

Question 2

Calibration Guidance for Dexcom CGM Systems

Accepted Answer

Do Dexcom sensors need calibration?No. Dexcom CGM systems are designed to work without routine calibrations. However, optional calibration is available across all Dexcom devices.Can Dexcom Sensors Be Calibrated?Yes, all Dexcom sensors support calibration, but it is not required for normal operation. These systems are factory-calibrated and intended to function accurately without user input.When Is Calibration Recommended?CGM systems measure glucose levels in the interstitial fluid, whereas conventional blood glucose meters (BGMs) measure glucose levels in the blood. Because these measurements come from different sources, CGM glucose values may differ from blood glucose values. These differences can be expected and CGM readings are still reliable for treatment decisions. *The %20/20 rule describes the acceptable deviation between fingerstick blood glucose readings and CGM interstitial glucose readings:For blood glucose readings ≥3.9 mmol/L (≥70 mg/dL), the sensor's glucose value may deviate up or down by 20% of this value.For blood glucose readings <3.9 mmol/L (<70 mg/dL), the sensor's glucose value may deviate up or down by 1.1 mmol/L (20 mg/dL) from itCalibration may be considered if:Your sensor readings differ from fingerstick values by more than expected under the %20/20 rule.You experience symptoms that do not match your CGM readings.You are using Dexcom G6 without a sensor code (in which case calibration is required).When Should You Avoid Calibration?Do not calibrate if:Your glucose is changing rapidly (e.g. after meals or exercise).There is pressure on the sensor (e.g. lying on it).You see a sensor error message.You are experiencing unstable readings with up/down trend arrows. Calibrating on an up or down arrow may fail the sensor. Wait until you have a horizontal arrow.Your device is displaying a message relating to sensor errorRemember frequent calibration of the device may cause exaggerated increases or decreases in glucose levels to show on the sensor, especially in the situation mentioned above. This could cause the sensor to detect an issue and fail. Only calibrate when necessary.There is the option to log your blood glucose without using it as a calibration. This can be done in the appIn the app, tap + in the Glucose, Log or History tab.In the receiver, go to Menu > Event > Blood Glucose.Select Blood Glucose, then Log Blood Glucose. Follow onscreen instructions to log blood glucose meter value.How to calibrate correctlyUse only fingerstick values from a blood glucose meter (not CGM readings).Wash hands thoroughly with soap and water (not gel cleaners).Enter the calibration within 5 minutes of taking the fingerstick.Calibrate using only one display device (app or receiver).Acceptable calibration range: 2.2–22.2 mmol/L.How do I calibrate my Dexcom device?In the app, tap + in the Glucose, Log or History tab.In the receiver, go to Menu > Event > Blood Glucose.Select Blood Glucose, then use as Calibration. Follow onscreen instructions to enter BG meter value as a calibration.deleteOther frequently asked questions on calibrationWhat does Calibration error mean?This means you have recently entered a calibration blood glucose, and the sensor is having trouble calibrating. Follow the directions on screen and recalibrate in 15 minutesWhat does calibration not used mean?This means the sensor could not use the glucose reading you entered as a calibration. Wait for 15 mins and try again.What does the blood drop icon mean?It means that you are required to do an additional calibration.*Slight differences between these readings are normal. BGM is not the gold standard and CGM readings should be compared to glucose levels in a patient’s vein using the YSI glucose analyser. Calibration should be considered if sensor readings differ from finger prick values by more than 20–30% or if there are symptoms that do not match CGM readings. Finger pricks are required for diabetes treatment decisions if symptoms or expectations do not match readings.

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