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Critical: No CGM Updates - Loop Failure #2265

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Critical: No CGM Updates - Loop Failure#2265

Description

@TravisWhip
TravisWhip
opened on Nov 19, 2024

CRITICAL

This is a critical issue as Loop is no longer functional!

Loop will only work for a short while if I manually enter a BG value.

Description of Bug

Randomly Loop will stop receiving CGM updates and halt all dosing.

Dexcom App and Direct-to-watch are able to get CGM updates just fine, however Loop is not receiving any CGM updates.

I have raised this issue in the past on Zulip (https://loop.zulipchat.com/#narrow/channel/148543-Loop/topic/Loop.20Failure/near/479067306). In the past I was able to get around this issue by:

  1. Delete CGM in Loop
  2. Quit Loop
  3. Quit Dexcom G7 App
  4. Forget all Dexcom sensors in Bluetooth settings
  5. Open Dexcom App & add G7 as CGM
  6. Open loop app
  7. Wait for pairing request from sensor

However, this time I cannot get around this issue.

Issue Report

Here is an export generated after updating loop to 3.4.4 (57) from develop 3.3.0 (57).
Export-20241119T013430Z.zip

After updating to 3.4.4 and still having the same issue I deleted Loop on my phone and all data, and re-installed Loop fresh. After doing this I still have the same issue. Here is another export after completely re-installing Loop:
Export-20241119T020829Z.zip

Pictures/Video

After deleting and re-adding the Dexcom G7 CGM, the CGM never connects / updates:
Full Size Image
Screenshot 2024-11-18 at 9 16 54 PM

Here is a short video showcasing that Loop has not updated in awhile and that the CGM is just "scanning":
https://github.com/user-attachments/assets/e847688b-facf-4a44-8577-ad3c7580d876

To Reproduce

Unknown at this time.

Expected behavior

Loop should get CGM updates while Dexcom G7 App is receiving updates.

Metadata

Phone

  • Hardware: Iphone 12 Mini
  • OS Version: IOS 17.5.1
  • Watch OS: 10.6.1

Loop Version

  • Version Number: 3.4.4
  • Repo: LoopKit/Loop

CGM

  • Device: Dexcom G7
  • Manager app: Dexcom App

Pump

  • Manufacturer: Omnipod
  • Model: Dash
  • Firmware version: N/A

Additional context

This issue has happened to me in the past and I was able to get around it by forgetting all Dexcom Bluetooth devices. However, this time doing these steps has not resolved the issue. Loop is currently unusable.

Activity

  1. marionbarker commented on Nov 19, 2024

    @marionbarker
    marionbarker
    on Nov 19, 2024
    Contributor

    This must be so frustrating for you.

    It might be helpful to see your Loop Report - the Dexcom traffic is included in there. (Loop, Settings, scroll down to support and tap Issue Report.)

    I'm baffled by these reports. Yours is not the only one.

    Some people reported it got better with the next sensor.
    Some people used the procedure you listed successfully.
    Did you add a phone reboot after forgetting all the bluetooth devices?
    Did you wait for the sensor to first pair with the Dexcom app and the first CGM value be reported, and only then restart the Loop app?
    Do you have other bluetooth devices connected to the phone?
    Do you have any other apps on the phone trying to interface with the G7 (xDrip4iOS, Trio, Suggah, etc.)?

  2. motinis commented on Nov 19, 2024

    @motinis
    motinis
    on Nov 19, 2024

    I wonder if it might be possible to work around this by implementing a new "Apple Health" CGM - basically it would be querying Apple Health for updates to BG. G7 App can write that data.

  3. marionbarker commented on Nov 19, 2024

    @marionbarker
    marionbarker
    on Nov 19, 2024
    Contributor

    Dexcom app writes to Apple Health with a 3 hour delay. Not useful for looping. However, you could try using Dexcom Share as CGM. It requires internet and isn’t an idea solution but it should work.

  4. scottf51 commented on Nov 19, 2024

    @scottf51
    scottf51
    on Nov 19, 2024 via email

  5. TravisWhip commented on Nov 19, 2024

    @TravisWhip
    TravisWhip
    on Nov 19, 2024
    Author

    So for the time being I am using a Dexcom Share CGM - but this requires constant internet connection.

    Environment

    Here is my current environment, please let me know if there is anything else that is noteworthy.

    CGM Related Apps

    I am not using any other application for CGM monitoring other than the Dexcom G7 app and Loop.

    Apple Health

    Only Loop is writing CGM data to Apple Health. My Apply Health history ends where loop initially failed. Dexcom G7 has been stable and reporting values since this issue started to now - no issues with Dexcom G7 directly (that I can tell).

    Issue Reports

    Hello @marionbarker, I have taken two Issue Reports and attached them below along with some context around them.

    Issue Report - Dexcom Share CGM

    This issue report was generated after using Dexcom Share as a CGM since re-installing Loop last night (around 9pm, EST).
    DexcomeShare_Loop Report 2024-11-19 11_22_22-05_00.md

    Issue Report - Dexcom G7

    ... While gathering this report the Dexcom G7 started working again...

    This issue report was generated after switching to using a Dexcom G7 CGM in Loop after the first report was generated. I expect to have CGM readings every 2nd and 7th minute.

    After exporting the first logs I performed the following:

    1. Removed Dexcom Share as CGM in Loop
    2. Added Dexcom G7 as CGM in Loop
    3. Deleted Dexcom Bluetooth from Bluetooth Devices in IPhone Settings (around 11:21 AM EST)
    4. Opened Dexcom G7 App to wait for Bluetooth pairing request
    5. At ~11:22AM EST I got a Bluetooth Pairing Notification
    6. Dexcom G7 App updated with CGM reading for 11:22
    7. Went back into Loop and there was no CGM reading for 11:22
    8. From 11:27 onward, Loop was able to get CGM readings, but did not backfill for the 11:22 CGM value
    9. Loop works fine. CGM value for 11:22 is still missing in Loop.

    DexcomG7Loop Report 2024-11-19 11_48_17-05_00.md

    Quick Investigation

    Comparing the DexcomShare and DexcomG7 issue reports, I can see a Device Communication Log I can see that at 11:23 AM, Loop tried to read from Dexcom:

    * 2024-11-19 16:23:04 +0000 G7CGMManager  error Sensor error Error enabling notification for authentication: unknownCharacteristic

    This looks to the 11:22 AM CGM value I am missing in Loop. I wonder if this is the error I was having yesterday (and in the past) preventing Loop from getting updated CGM values.

    From this point on, I can see G7CGMManager logs for Connecting, Reading, Disconnecting - every 5 min as everything is working now. Example of log grouping:

    * 2024-11-19 16:33:04 +0000 G7CGMManager DXCMqb connection Sensor connected
* 2024-11-19 16:33:05 +0000 G7CGMManager DXCMqb receive Sensor didRead G7GlucoseMessage(glucose:Optional(90), sequence:2187 glucoseIsDisplayOnly:false state:ok messageTimestamp:654805 age:6, data:4e00d5fd09008b08000106005a0006ff57000f)
* 2024-11-19 16:33:10 +0000 G7CGMManager DXCMqb connection Sensor disconnected: suspectedEndOfSession=false

    Critical Event Logs - After Loop started working again

    Since loop started working again, here are the critical event logs after loop started working:
    Export-20241119T163157Z.zip

    Current Status

    Loop is now working again with the Dexcom G7 sensor directly... I am not sure what has changed from last night to now, other than running with the Dexcom Share CGM for the time being.

    I am now able to use the Dexcom G7.

  6. andrewhemp commented on Nov 19, 2024

    @andrewhemp
    andrewhemp
    on Nov 19, 2024

    My G7 just started having this same issue not uploading readings. It started at 12:05pm
    image
    Loop Report 2024-11-19 125616-0600.md

  7. TravisWhip commented on Nov 19, 2024

    @TravisWhip
    TravisWhip
    on Nov 19, 2024
    Author

    @andrewhemp, to keep this thread clean, is there any additional context / logs you can provide in addition to what I have provided?

    PS, use Dexcom Share as your CGM for the time being. Then every few hours try using the Dexcom G7 CGM until it works - at least that's what I did.

  8. andrewhemp commented on Nov 19, 2024

    @andrewhemp
    andrewhemp
    on Nov 19, 2024

    @TravisWhip mine started working after awhile. I removed my CGM from loop, airplane mode, closed all apps and restarted phone. Not sure what was going on, I did notice the Dexcom servers were down when I tried to use share at first.

  9. alliemakes commented on Nov 20, 2024

    @alliemakes
    alliemakes
    on Nov 20, 2024

    We have not been able to get the G7 to pair at all with Loop. We are a new to Looping and this is a new build and just trying to get everything set up and it just says searching. We have tried all the above steps to get it to connect: deleting app, deleting dxm values in bluetooth and shutting down apps and restarting. It will not connect to Loop. It is displaying in the Dexcom app and sharing to the follow app.
    I am unsure what Dexcom Share is, unless you mean Dexcom Follow. If it is the Follow app, I am unsure of how to make that work together. All help is very appreciated.Thank you

  10. TravisWhip commented on Nov 22, 2024

    @TravisWhip
    TravisWhip
    on Nov 22, 2024
    Author

    @alliemakes, it's a CGM option in Loop.

    See the CGM section of Loop's documentation here: https://loopkit.github.io/loopdocs/loop-3/add-cgm/

    image

  11. marionbarker commented on Mar 14, 2025

    @marionbarker
    marionbarker
    on Mar 14, 2025
    Contributor

    There is an open PR to G7SensorKit that is improving G7 connectivity as long as the Sensor is communicating with the app. It is not perfect and some people are still having trouble.

    Please see: LoopKit/G7SensorKit#33

    This can be added to released version of Loop (see G7 Missing Readings option) using a the Customization Select Script:

  12. timd24 commented on Mar 19, 2025

    @timd24
    timd24
    on Mar 19, 2025

    Following this issue closely. This is the most challenging bug I’ve seen in the app in many years.

  13. marionbarker commented on Apr 24, 2025

    @marionbarker
    marionbarker
    on Apr 24, 2025
    Contributor

    Closed with Loop release 3.6.0

  14. marionbarker
    closed this as completedon Apr 24, 2025

  15. tomleim commented on Jul 31, 2025

    @tomleim
    tomleim
    on Jul 31, 2025

    I needed to delete the Loop app from my phone before installing Loop 3.6.3 for this fix to take. For some reason going through the initial steps where you grant Bluetooth permission in Loop might be necessary.

  16. amy-inkster commented on Aug 3, 2026

    @amy-inkster
    amy-inkster
    on Aug 3, 2026

    First time commenting, if this is not helpful or not the right place for this feel free to delete. I found this thread from the other #2286

    I have just started having this issue in July 2026. Loop stops finding G7 even though the G7 app is still functional and fully connected. Using Loop v3.8.1(57) on an iPhone 17, running iOS 26.5.1. This connectivity issue has only arisen in the last two G7 sensors I have had, maybe related to an iOS update but I can't place the date I updated exactly.

    For me this issue has only happened twice, both times within an hour of my G7 session ending and the grace period starting. Both times, it couldn't seem to be fixed before the grace period has started (I tried several times to fix, following all steps above: forget sensor in G7 and loop, turn off bluetooth, restart phone, turn on bluetooth, re-pair sensor in G7 app before opening loop and adding a new CGM). After these steps before grace period ended while sensor session was still active loop gets stuck "searching for sensor". After the sensor session officially ended and the grace period started, by following the exact same set of steps after opening loop it was then able to locate the sensor and connect, closing the loop successfully.

    Key for me was noticing that this was proximal to the transition to the G7 grace period. May be helpful?

  17. blameitonben commented on Aug 3, 2026

    @blameitonben
    blameitonben
    on Aug 3, 2026 via email
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