Accuracy And Calibration - Dexcom ONE+ User Manual

Accuracy and calibration

Issue
Why aren't your BG meter value and sensor reading exactly the same?
Solution
Accuracy
One reason is they're measuring glucose in different fluids. The BG meter measures blood glucose while the sensor measures
interstitial fluid. And if your healthcare provider 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 BG meter and your Dexcom ONE+ are:
Hand cleanliness: Wash your hands with soap and water (not hand sanitizer) and dry them. Then test. Many inaccurate
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BG meter values are from hands not being washed thoroughly before testing.
Sensor's first day: With newly inserted sensors, the differences between your BG meter and the sensor reading may be
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greater. Generally, the numbers get closer over the first 24 hours.
Pressure on sensor: Sometimes when something is pressing on your sensor, for example, if you're lying on it, it can
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affect your sensor readings. Relieve the pressure and the numbers should get closer.
Glucose changing quickly: When your glucose is rapidly changing, it can be more difficult to compare your BG meter
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value and sensor reading because blood glucose changes a little before interstitial fluid glucose. The numbers should get
closer when your glucose stabilizes.
Test strips: Make sure your test strips are stored as directed and not expired. Also, make sure to use enough blood on the
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test strip.
You can log your BG meter value by tapping the plus sign (+) in the Glucose or History tabs.
In the receiver, go to Menu > Events > Blood glucose > Use as calibration. If Events isn't an option on your Dexcom ONE+
receiver menu, go to Menu > Calibrate sensor.
If your sensor readings are always much higher (or always much lower) than your BG meter values for several hours, consider
calibrating your Dexcom ONE+.
Calibration
Calibrating your Dexcom ONE+ is optional. It can make Dexcom ONE+ more accurate or less accurate compared to the lab
result, but it should bring the sensor readings closer to your BG meter value.
Don't calibrate in these situations:
Sensor site pressure: Don't calibrate if the sensor reading seems inaccurate because of pressure on the sensor. The
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sensor should recover on its own when the pressure is relieved.
Rapidly changing glucose: Calibration works best when your glucose is stable. Consider waiting to calibrate if your
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glucose is changing rapidly.
When calibrating, make sure to:
Clean hands: Wash your hands with soap and water and dry them.
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Enter within 5 minutes: Enter the calibration within 5 minutes of taking a fingerstick.
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12 • Troubleshooting | Dexcom ONE+ User Guide
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