Trio Follower is an Android app that reads data from Nightscout and shows it in a familiar layout resembling Trio. It is specifically built to get data uploaded by Trio, and will probably not work well with data uploaded from other OSAID systems.
You can use it in two ways:
- Follow your own Trio data from an Android device.
- Follow a person with diabetes as a caregiver, for example a parent whose child uses Trio.
The app only shows data and sends alerts. It cannot control a pump or change any settings in Trio.
| Home | Inspect a point in time | Algorithm reasoning |
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| History | Settings | Widgets |
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- An Android device with Android 12 or newer. The app is built to support phones, not tablets or foldable phones.
- Someone using Trio on an iPhone, with Trio uploading to Nightscout.
- A Nightscout site that is running and reachable from the internet. You need its URL and an access token. Nightscout has to support the v3 API. Nocturne should also work, but limited testing has been done.
Home
- Glucose bubble with the current value, trend arrow, minutes since the reading and the change since the last one. Tap it to read the algorithm's reasoning for that reading.
- A chart you can scroll and zoom. It shows glucose, basal, boluses, carb entries, insulin on board, carbs on board, overrides and temp targets.
- Press and hold on the chart, then drag, to see the time, glucose, IOB and COB at any point. Dragging near either edge scrolls the chart.
- Predictions on the chart, drawn as lines or as a cone. You can also turn them off.
- Small status pills for reservoir, insulin on board, carbs on board, pump and sensor age, and the algorithm's eventual glucose.
- A notice on the Home screen when a newer version is available on GitHub, with what changed. You can turn the check off in Settings.
- A statistics bar with today's time in range, or your average glucose.
- Two home screen widgets: one with just the glucose bubble, and one with the bubble and a graph of the last 6 hours plus the 2 hour forecast. You choose how transparent each one is when you add it.
History
- Treatments, meals, glucose readings and adjustments. Tap a glucose reading to see the algorithm's reasoning for it.
Alarms
- Glucose alarms: urgent low, low, high and urgent high, each with its own threshold.
- Additional alarms, each with its own limit:
- Predicted high, for a slow climb inside your range. Handy when a pump site fails.
- No data, if no new glucose arrives for 20, 40 or 60 minutes.
- Not looping, if Trio has not looped for 20, 40 or 60 minutes.
- High insulin on board or high carbs on board.
- Low reservoir.
- Sensor change due and pump site change due, a set number of hours before it runs out.
- Low battery on the Trio phone (the iPhone running Trio, not the phone running this app).
- Random alarm, which goes off a few times a day for no reason at all. For when the other alarms don't give you enough alarm fatigue.
- Every alarm can be turned on or off, and set up on its own: sound, vibration, acknowledgement, and repeat until acknowledged.
- Day and Night windows: set your own day and night hours, and choose for each alarm whether it goes off during the day, at night, or both.
Updating data
- Data refreshes when you open the app, and on your chosen interval while the app is open.
- Background sync keeps alarms working when the app is closed.
- Choose battery friendly, or real-time with a notification that shows the current glucose.
- Alarms work better when real-time is selected.
Settings
- mg/dL or mmol/L, and 12 or 24 hour time.
- Dynamic or static glucose colors.
- An option to keep the screen on.
- A diagnostic log you can export if something does not work.
There are two ways to install the app:
- Download from GitHub Releases: get the latest APK from the releases page and open it on your phone. Android asks you to allow installs from your browser or file manager the first time.
- Build it yourself: open the project in Android Studio, let Gradle sync, and build an APK using your own signing certificate.
If you switch between a downloaded APK and one you built yourself, uninstall the app first. Android refuses to update an app that was signed with a different key.
Updates: the app checks GitHub about once a day. When a new version is out, a card on the Home screen shows what's new, with a button that opens the download page. You can turn the check off, or check by hand, in Settings > Information and Releases.
Trio Follower is written in Kotlin. The screens use Jetpack Compose with Material 3. It is built with Gradle and needs Android 12 (API 31) or newer.
Main dependencies:
- Jetpack Compose, Navigation, Lifecycle and Activity for the interface.
- Room and DataStore for the local cache and the settings.
- WorkManager for background sync.
- Hilt for dependency injection.
- Retrofit, OkHttp and kotlinx.serialization for the Nightscout API.
- AndroidX Security for storing the access token.
The app is developed with code assistance from Claude Code, an AI coding assistant. The developer reviews and tests the changes.
Trio Follower is a hobby project made by an enthusiast for personal use. It is open source and comes with no warranty. The developer is also a contributor to the Trio project, but Trio Follower is not affiliated with the Nightscout or Trio projects. Several features and design elements are borrowed from Trio. A big thank you to the entire Trio developer team and community!
Please understand that Trio Follower is:
- used entirely at your own risk
- not CE or FDA approved for therapy
- not a medical device, and not for making medical decisions
Data can be late, wrong or missing, and alarms can fail. Never rely on this app alone. Always check your pump, your CGM and Trio itself before you dose or act on any reading.
MIT. See LICENSE.