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CGM Configuration

CGM Choices

A CGM can be added from the Heads-Up-Display (HUD) or from the Loop Settings screen.

The HUD will look like the graphic below if no CGM or Pump is connected with Loop:

Loop HUD when CGM and Pump have not been added

Loop can be connected to the following CGMs:


To add a CGM, go to the Settings screen, tap on add CGM and tap on your CGM.

graphic showing some of the CGMs available with Loop 3

Dexcom G5, G6, ONE

To use the Dexcom G5, G6 or ONE:

  • Select Dexcom model, use G6 for either G6 or ONE
  • Dexcom app must be running on the Loop iPhone and paired to an active transmitter
  • User must enter that active transmitter ID in the location indicated by the red rectangle in the graphic below
  • Do not enter your Share Credentials
    • The graphic below shows Tap to set
    • Do not tap, leave it alone
  • Only add the transmitter ID to Loop after it is paired with the Dexcom app on your phone

interface to add transmitter ID for Dexcom

FYI: When You Change Transmitters

Before you change Dexcom transmitters, select the Delete CGM button at the very bottom of the CGM info page in Loop. Then, follow Dexcom Instructions for changing transmitters. Once the new transmitter is paired with the Dexcom app, go to the CGM page in Loop, tap Add CGM and enter the new transmitter ID. You cannot just tap on your old transmitter ID to update it.

If you don't update your transmitter ID in Loop after you change the transmitter in Dexcom app, Loop will not get CGM data from the Dexcom app on your phone.

About Dexcom Share credentials

You do NOT need your Share account info listed in Loop settings if you are using a G5 or G6 system. The transmitter ID is sufficient. In fact, you should leave your Share credentials blank so that you don't accidentally become internet-dependent for CGM data if you forget to update your transmitter ID when you start a new transmitter.

Dexcom G7

This is only available on Loop dev and requires special build instructions (as noted above).

You must have the G7 app on the same phone as Loop.

Minimal documentation is provided and this is an in-process implementation. Please join zulipchat and click on the Development G7 Integration link to read the conversation.

Medtronic Enlite CGM

The Medtronic Enlite CGM is only available if you have connected it to your compatible Medtronic Pump.

  • Make sure your pump reports the Enlite CGM results
  • Go through the Add Pump to Loop steps with that Medtronic pump
  • Then do the Add CGM steps and the sensor should be presented as an option

Dexcom Share as a CGM

If you need to use Dexcom Share

If the dexcom is on another phone, you can use Share if internet / cell coverage is good.

Dexcom Share is not available for Dexcom ONE CGM.

The Dexcom Share credentials (in other words, account login) is the same as what you used to log in to the active Dexcom app on your iPhone. Dexcom Share account is not always the same login info as your Dexcom Clarity account. The information is entered when you first log in to the app and then is never displayed again, nor visible under any information screens. If you have forgotten your G5/G6 account info, you can delete the Dexcom app and redownload it to try logging in again. This will not cause a restart of any sensor sessions in progress.

If you do not enter your Share credentials correctly into Loop, you will get an error when Loop tries to access your Share account to backfill CGM data. An example of the error message is shown in the graphic below. If you see that message, delete your Share account from Loop settings and try again.


Nightscout Remote CGM

If the user is already uploading CGM data to their Nightscout URL, they can select that as a source for CGM data for Loop. The user must acknowledge they understand the risks of using a remote source that requires internet, as shown in the graphic below.

In addition to the risks of missing data if the internet is not reliable, you must also make sure the CGM data sent to Nightscout is reliable.

DANGER - Make sure Nightscout CGM Data is Reliable

Just because you can use Nightscout as a CGM source does not mean you should.

If you decide to use Nightscout as a CGM source, make sure the data stored in Nightscout is reliable. If the app you choose uploads bad results to Nightscout, you don't want Loop to use that bad data.

Sensors that can be added to Nightscout via other apps include Dexcom, some Libre and some Medtronic sensors. Please refer to Nightscout Docs: Configure your Uploader.

There are third party apps that bring Libre data to your Loop phone and there are customization instructions starting at Add Libre App to Loop Phone that explain how to modify Loop dev to use one of those apps. Please use these steps to get a version of Loop that does not rely on internet access to work.

It is recommended that you use Open Loop during warmup until the new sensor begins to provide reasonable data. This is especially important with European Libre 2 using direct bluetooth connection.

The xDrip4iOS app (which can also be found in the app store under the name Shuggah) may have a problem during warmup of a new sensor (European Libre 2 using direct bluetooth connection). There were two instances of crazy high values being reported and picked up by Loop dev. One Shuggah user and one xDrip4iOS user who connected via Nighscout as a CGM with Loop dev had serious overdose of insulin because of bad readings with a new sensor. They are both OK but the Loop and xDrip4iOS developers are looking at this event.

Nightscout Remote CGM acknowledgement screen

The user must enter both the URL and API_SECRET for their site to ensure the security of the data. The URL must start with https:// and cannot have any extra spaces in the line.

Nightscout Remote CGM entry screen

When using Nightscout Remote CGM, if the user needs to change credentials or switch to a different CGM, the user must go through the Loop->Settings->CGM menu.

Change CGM

To change CGMs, delete your existing CGM and then add a new CGM.

  • For Dexcom G5, G6, ONE or Share, access Delete CGM by tapping on the CGM Icon in the HUD or by tapping on Loop Settings and selecting CGM and scrolling down.

  • For Nightscout Remote CGM, the Nightscout URL is opened when tapping on the CGM icon in the HUD, while the credential sections with the Delete CGM row is shown when tapping on Loop Settings and selecting CGM.

After deleting a CGM, the Head-Up-Display at the top of the Loop main screen will show the add CGM icon.

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