Native Algorithm

xDrip » Features » Dexcom » Native Algorithm

The sensor has no direct access to blood. It has access to interstitial fluid. The interstitial fluid glucose and blood glucose are correlated. The sensor measures glucose in interstitial fluid. From that, the CGM calculates the blood glucose. A formula is used to do the calculation. When we perform a blood glucose measurement, with our glucose meter, and enter the reading into the continuous glucose monitoring system (CGM), and perform a calibration, the CGM updates the formula using the current interstitial fluid glucose and the blood glucose reading we just entered.

When we use the native algorithm, the transmitter maintains the calibration formula. In non-native mode, xDrip maintains the formula. The two modes are compared in the following table.

  Native Non-Native Notes
To choose Enable: Disable: Settings −> G5/G6/Dex1 Debug Settings
−> Native Algorithm
Backfill Yes No Last 3 hours
Session stops after
10 days (7 for G5)
Yes No In native mode, only preemptive restart
will keep the sensor going.
G6 factory calibration Yes No  
Transmitter stops after
110 days (112 for G5) *
Yes No ** Transmitter hard reset will reset the
number of days to 0.
Relevant Calibration Graph No Yes ***
Clear calibrations No Yes ***

* The last day you can start a sensor in native mode is when transmitter days shows 99 (104 for G5).

** If the G6 transmitter firmware version is or prior to that, it transmits raw values as well. Therefore, it can be used in non-native mode. All G5 transmitters can be used in either native or non-native mode.
Native mode is automatically enabled for a G6 except in engineering mode.

*** In native mode, calibration is done by the transmitter. If you see a calibration graph, it is because the transmitter sends raw values also. But, the graph does not represent the calibration formula. Clearing calibrations in native mode will have no impact on the effective calibration formula.