Common questions and answers about the CGM Data App for Garmin watches.
A: The app fetches new glucose readings every 5 minutes, which matches Dexcom's standard update interval.
In typical use, you'll see updates every 5-8 minutes. The first update happens right away, but the second one will take beteween 5 and 9 minutes as the app will try to sync up exactly to Dexcom's schedule. Due to Garmin limitations, the app can only access the internet once every 5 minutes while in the background. To sync up with Dexcom, it reads the time it was last updated on Dexcom's end, and plans the next update 3 seconds after the expected time Dexcom will update the data again, so in theory your data should show up within ~15 seconds of the last reading.
A: Trend arrows indicate the direction and rate of change of your glucose levels. Here's what each arrow means:
| Arrow | Meaning | Rate of Change (Dexcom) |
|---|---|---|
| → | Steady | -1 to +1 mg/dL/min or less than 15 mg/dL in 15 minutes |
| ⬈ ⬊ | Rising or Falling slowly | 1 to 2 mg/dL/min or 15-30 mg/dL in 15 minutes |
| ↑ ↓ | Rising or Falling | 2 to 3 mg/dL each minute or 30-45 mg/dL in 15 minutes |
| ↑↑ ↓↓ | Rising or Falling rapidly | > 3 mg/dL each minute or more than 45 mg/dL in 15 minutes |
A: Currently, this app only supports Dexcom G6 and G7 systems that use Dexcom Share. Other CGM systems are on the way
A: No, Dexcom Stelo is not currently supported. The app only works with Dexcom G6 and G7 systems that have Dexcom Share enabled. Stelo uses a different system and API that is not compatible with this app at this time.
A: No, the app requires your phone to be connected via Bluetooth and have an active internet connection. The CGM data is fetched from Dexcom Share servers through your phone, not directly from your transmitter. The last known reading will continue to display on your watch up to 10 minutes, but it won't update without connectivity. After 10 minutes of no updates, no data will be displayed.
A: The CGM data app is designed to be very battery efficient:
A: Currently no, no alerts can be enabled on this app, this is a feature that might be added in a future update. For now, you can use more reliable ways of settings alerts:
A: Small differences can happen due to synchronisation time. Since the app can only update once every 5 minutes, it can get behind by up to 10 minutes.
Always trust your primary Dexcom device for medical decisions and do never rely on this app in any case.
A: Your credentials are:
As with any password, use a strong unique password for your Dexcom account.
A: The Dexcom Share API reports "invalid password" for various authentication issues. Here are common causes:
If you've verified all of these and still have issues, see the Error Codes page for more troubleshooting steps.
A: This means the CGM app hasn't been configured yet or couldn't retrieve data. To fix this:
See the Installation & Setup guide for detailed instructions.
A: Currently, no. A datafield app is on the way to make this happen.
A: If you change your Dexcom Share password, you must update it in the Garmin app:
The app will show an "Auth Failed" error until you update the password.
A: No. The app requires:
During airplane mode or when disconnected, the last known reading will remain displayed but won't update.
A: Both options connect to your Nightscout site, but they work differently:
Recommendation: Use regular Nightscout (with proxy) if you want to see more historical data on your watch. Use Nightscout Direct if you prefer a direct connection and only need recent readings.
A: No. All your personal data is stored only on your Garmin device.
To display up to 24 hours of glucose history on your watch, your data is temporarily passed through a service located in the EU or US (based on your location). This service processes the data to reduce its size so it fits within Garmin's memory constraints.
Important: No data is stored by this service. No traces are left. The service only compresses data in transit and passes it directly to your watch. Your credentials and glucose readings remain private and are never logged, analyzed, or retained.
A: Yes, the CGM Data App is completely free to download and use. If you find it useful, consider supporting the developer through Ko-fi or other donation platforms linked in the app description.
More Help: Check Error Codes for troubleshooting or return to Introduction.