What do I do if my Dexcom G7 CGM values seem inaccurate?
The numbers on your Dexcom G7 Continuous Glucose Monitoring (CGM) System may differ compared to your Blood Glucose Meter (BGM), or glucometer, values because they're measuring glucose in different fluids. BGM measures blood sugar levels while the Dexcom G7 sensor measures glucose levels in your interstitial fluid. BGM and CGM may show different numbers, but both can still be accurate. If your diabetes care team did a lab test at the same time, the lab result may give a third number. The lab test is considered the most accurate number.
Other reasons there could be a difference between your BGM and Dexcom G7 CGM readings are:
- Hand cleanliness: Wash your hands with soap and water and dry them. Then test. Many inaccurate BGM values are from hands not being washed thoroughly before testing.
- Sensor’s first day: With newly inserted sensors, the differences between your BGM and the sensor reading may be greater. Generally, the numbers get closer over the first 24 hours.
- Pressure on sensor: Sometimes when something is pressing on your sensor, it can affect your sensor readings. Relieve the pressure and the numbers should get closer.
- Glucose changing quickly: When your glucose levels are rapidly changing, it can be more difficult to compare your BGM value and sensor reading because blood glucose changes a little before interstitial fluid glucose. The numbers should get closer when your glucose levels stabilise.
- Test strips: Make sure your test strips are stored as directed and not expired. Also, make sure to use enough blood on the test strip.
You can log your BGM value by tapping + in the Dexcom app's* Glucose or History tabs. In the receiver,* go to Menu > Event > Blood Glucose.
If your sensor readings are always much higher (or always much lower) than your BGM values for several hours, consider calibrating your Dexcom G7.
Calibration
Calibrating your Dexcom G7 is optional. It should bring the sensor readings closer to your blood glucose meter value.
* Display devices sold separately. For a list of compatible smart devices, please visit www.dexcom.com/compatibility. The optional receiver may be purchased through the Dexcom Store.
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