Smoothing blood glucose data

If BG data is jumpy/noisy, AAPS may dose insulin incorrectly resulting in highs or lows. If you observe errors or experience jumpy data with your CGM it is important to disable the loop until the problem is resolved. Depending on your CGM, such issues may be due to the CGM configuration in AAPS (as explained further below); or a CGM sensor site issue (which may require replacing the CGM sensor).

Smoothing data within AAPS

AAPS offers the option to smooth the data within AAPS rather than within the CGM app. Open the menu (☰), select Configuration, then Smoothing. There are four options, and only one can be active at a time: No smoothing, Exponential smoothing, Average smoothing and Unscented Kalman Filter.

Exponential smoothing

In general, this is the recommended option to start with, as it is most aggressive in resolving noise and rewrites the most recent value. However, see the table below for other specific recommendations.

Average smoothing

This option works similar to back smoothing that was previously implemented on certain CGM platforms. It is more reactive to recent changes in BG value and therefore more prone to responding incorrectly to noisy CGM data.

No Smoothing

Use this option only if your CGM data is being properly smoothed by your collector app before being transmitted to AAPS.

Unscented Kalman Filter (UKF)

This option uses a statistical model to continuously estimate your true glucose value and its rate of change from the incoming (possibly noisy) readings, automatically adapting to how noisy your sensor currently is. It also detects and rejects sudden outlier readings. It is a more advanced alternative to Exponential and Average smoothing, useful if you want the smoothing to adjust itself to your sensor’s changing noise level rather than using a fixed method.

Suggestions to use smoothing

You can also change the smoothing method automatically, for example depending on the sensor age, with the Change smoothing Automation action.

	Exponential	Average	No Smoothing
G5/G6/ONE	If noisy		Recommended
G7/ONE+/Stelo	If noisy	If stable

Libre sensors are noisy and can require smoothing. When using xDrip direct connection, or the patched app data source (receiving from another app, Juggluco included), smoothing is already done inside the app.

Sensor / Data source	Juggluco	xDrip direct	xDrip bridge	xDrip patched app
Libre 1/14 days/Pro	N.A.	N.A.	Average	N.A.
Libre 2/2+ (EU)	Average	None	Average	None
Libre 2/2+/3/3+	Average	N.A.	N.A.	None