When and how often should I calibrate?

You should calibrate when the system requires it or if the CGM reading is inaccurate. You can calibrate when you are asked for the two start-up blood sugars,


when prompted by the 12-hour calibration prompt,


and whenever the sensor is inaccurate. Inaccuracy is defined as when the difference between your sensor glucose reading and blood glucose value is greater than 20% of the blood glucose reading and blood glucose value is greater than 20% of the blood glucose value for sensor readings > 80mg/dL or greater than 20 points for sensor readings < 80 mg/dL.

When you do find the need to calibrate you will want to follow the steps below:

1. Take a blood glucose measurement using your meter
2. From any trend graph, press center (or select) button to display main menu
3. Use the up and down button to scroll until you highlight “Enter BG”
4. Press the center button to choose this option. You will see a screen with a blood drop and a number in mg/dL units

Once you dial in your blood glucose reading you will need to press “OK” again to confirm the value.

5. You will see the screen below afterwards, which shows that the Dexcom receiver is processing the calibration entry.