Understanding the Basics of Continuous Glucose Monitoring
Continuous glucose monitors (CGMs) like Dexcom are valuable tools for individuals managing their blood sugar levels. They provide real-time glucose readings, which can significantly aid in better health management. However, ensuring that the readings from your CGM are accurate is crucial to avoid potentially dangerous situations.
Why Discrepancies Occur
A common concern among CGM users is the difference between readings from their Dexcom and a traditional glucometer. This discrepancy arises because CGMs measure glucose levels in the interstitial fluid under the skin, which typically lags 5 to 10 minutes behind actual blood glucose levels measured directly from blood samples.
Recognizing When Readings Differ
When blood sugar levels are stable, CGM and glucometer readings should be close. Significant differences often occur during rapid changes in blood sugar levels. In such instances, the CGM might be “playing catch-up,” which is entirely normal due to the lag time in readings.
How to Determine CGM Accuracy
Dexcom provides a rule of thumb for accuracy: the CGM is considered accurate if it falls within 20 mg/dL or 20% of the glucometer reading. For example, if the glucometer reads 100 mg/dL, a CGM reading between 80 and 120 mg/dL is accurate.
Assessing Your Tolerance for Errors
While the guidelines suggest a 20 mg/dL deviation is acceptable, this may not always be sufficient for every user. Some prefer tighter accuracy standards and may choose to calibrate their sensors if readings deviate significantly.
Steps for Calibrating Your Dexcom CGM
Should you find your CGM requires calibration, begin by confirming the accuracy of your glucometer readings. Wash your hands, ensure they are dry, and perform two to three finger stick tests. Use these consistent readings for the calibration process.
Calibration Process for Dexcom T7
To calibrate your Dexcom T7, open the app, click on the plus sign, and select ‘BL glucose’. Enter your verified blood glucose number for calibration, save the changes, and confirm. It may take a while for the sensor to adjust to the new calibration.
Frequency and Timing of Calibrations
Calibrations are not needed frequently. They are typically required within the first or last 24 hours of the sensor’s life. Regular checks with a glucometer every few days can help ensure ongoing accuracy.
Navigating Sensor Faults
Occasionally, you may encounter a sensor that won’t calibrate despite repeated efforts. In such cases, contact Dexcom for a replacement. It’s a rare occurrence, as most sensors work well with calibration adjustments.
The Importance of Ongoing Monitoring
When using a CGM like Dexcom, it’s crucial to periodically cross-check its readings with a glucometer, particularly if you suspect inaccuracies. By maintaining a diligent routine of monitoring and calibrating, you can ensure more reliable glucose management.
