[feature request] - Add a warning if G6 is used, but readings are only pulled from Dexcom Share, indicating a wrong transmitter ID

[bjornoleh]

Is your feature request related to a problem? Please describe.

If Dexcom Share is configured in the G6 CGM setup, and the transmitter ID is wrong or not updated upon change of transmitted, the user will become dependent on internet connection (and the Dexcom Share server being operational). This is a rather common scenario, and the recommendation for Loop in LoopDocs is actually to not enter the Share credentials to avoid this trap.

I propose we rather make the required changes so that internet dependence will not go unnoticed by the user. This will allow users to get the benefit of backfilled readings when returning from out of bluetooth range, without the risks of unnoticed internet dependency after transmitter changes.

From LoopDocs:

About Dexcom Share credentials

You do NOT need your Share account info listed in Loop settings if you are using a G4, G5, or G6 system. The transmitter ID is sufficient. In fact, the recommendation is that you leave your Share account empty so that you don't accidentally become internet-dependent for CGM data when you forget to update your transmitter ID when you start a new transmitter. Just leave the Share credentials blank.

...

If you don't update your transmitter ID when you change active transmitters, your Loop will not get CGM data from the Dexcom app.

If you did add Share credential, Loop will get data from your Dexcom Share server and will not work without cell or wifi connection.

Loop does display a cloud icon that is intended to make users aware, but this has proven to be too inconspicuous, and does not prevent people falling into the internet dependency trap:

When Loop is using data from Dexcom Share servers, a small cloud will appear above the glucose reading in Loop and should tip you off that maybe you forgot to update your transmitter ID.

Describe the solution you'd like

Add a warning if G6 is used, but readings are only pulled from Dexcom Share, indicating a wrong transmitter ID.

The warning should only be issued after some time, as to not trigger upon backfills. I propose a proper warning to pop up, but a "cloud icon" indicator on or near the GCM value could also be useful too.

Describe alternatives you've considered

No alternatives comes to mind.

User Impact

Judging the reports in Looped FB and the LoopDocs recommendations, this has a big impact.

[LiroyvH]

I don't use Dexcom Share, so how do you get to this? It automatically falls back to Dexcom Share? Or is this the same situation as when you remove the G6 and it automagically falls back to Nightscout instead. (Shows it in dropdown, but no warnings on glucose source there either.)

[dnzxy]

it automagically falls back to Nightscout instead. (Shows it in dropdown, but no warnings on glucose source there either.)

that should not happen anymore with Trio as there's now a proper "no CGM chosen" option and doesn't just default to NS-as-CGM. have you run into it? 👀

[LiroyvH]

@dnzxy I'll try again on next sensor change :)

[github-actions]

hey 👋 - silence for 30 days 🤐 ... anybody? triage is required!

[bjornoleh]

I don't use Dexcom Share, so how do you get to this? It automatically falls back to Dexcom Share? Or is this the same situation as when you remove the G6 and it automagically falls back to Nightscout instead. (Shows it in dropdown, but no warnings on glucose source there either.)

You can optionally enter your Dexcom Share credentials in the G6 CGM configuration. This allows readings to be backfilled after the phone has been out of range of the transmitter. The problem is that it can also cover up the mistake of not changing the transmitter ID in Trio (remove G6 as CGM sources and add it back in with the new ID) when changing the transmitter. This allows internet dependency to creep up on users.