Here are some other common reasons why your BGM and CGM readings could differ:
Hand cleanliness: Many inaccurate BGM values are caused by hands not being clean. Wash your hands with soap and water (and dry them) right before testing.
Sensor’s first day: The difference between your BGM and CGM readings may be greater when you insert a new sensor. Generally, the readings get closer over the first 24 hours.
Pressure on your CGM sensor: When something is pressing on your sensor, it can affect your readings. Relieve the pressure and your BGM and CGM readings should get closer.
Rapid glucose change: It can be tricky to compare your BGM and CGM readings when your glucose is changing quickly, since blood glucose changes before interstitial fluid glucose does. The numbers should get closer when your glucose stabilizes.
Test strips: If test strips aren’t stored properly or are expired, they may not work correctly. Make sure your test strips are stored as directed and not expired, and that you use enough blood when testing.
Calibrating vs. Comparing
Calibrating your CGM system using your BGM reading is optional, but it can help align your CGM values with your BGM values. Calibrating is when you take a fingerstick and enter that BGM reading into your Dexcom CGM app as a calibration.
Comparing is when you take a fingerstick and use the BGM reading for your awareness. The G7 App also allows you to log that BGM reading without using it as a calibration for tracking purposes.
