Continuous glucose in Vitality Tracker

A continuous glucose monitor (CGM) is a small sensor worn on the back of the upper arm. It measures glucose in the fluid just under the skin every minute or so and keeps about a fortnight of readings. You never see a needle after the moment you apply it, and you never prick a finger. Vitality Tracker reads those glucose values, stores them, shows them, and — if you ask — tells you when they go outside a range you choose.

Vitality Tracker is not a medical device. It does not diagnose anything, it cannot be relied on for urgent alerts, and it must never replace the alarms in your sensor’s own app. If you manage diabetes, your CGM’s own app remains the thing you trust. Everything here is for understanding patterns, not for treatment decisions.

Which sensors work

FreeStyle Libre 2+

Fully supported and tested. This is the sensor Vitality Tracker was built and verified against. Set-up walkthrough →

Ottai, xDrip and similar

Supported through a bridge. Any app that can upload to a Nightscout-style endpoint can feed Vitality Tracker. How →

Libre 3 and Libre 3+ have never been tested. They may work, they may not, and we have no evidence either way — nobody on the team has worn one. Abbott changed how Libre 3 communicates, so please assume it does not work until we can say otherwise. If you have a Libre 3 and try it anyway, we would genuinely like to hear what happened.The same applies to Dexcom, Medtronic and Eversense: no direct support. Some can be bridged — see other CGMs.

What Vitality Tracker does with your readings


Shows them	The Live Dashboard: a scrollable trace back through your whole history, with your meals, fasts and sleep marked on it
Summarises them	Daily average, morning fasting glucose, estimated HbA1c, time in range, sensor coverage
Shares them	Writes to Apple Health or Health Connect so your other apps can see them — details
Watches them	Optional high and low alerts at thresholds you set — details
Checks the sensor	Warns you when readings stop looking believable, and lets you delete a stretch of bad data

The honest limits, before you start

We would rather you knew these up front than discovered them.

On iPhone, readings are only dense while the app is open

Vitality Tracker fetches your glucose every two minutes while the app is on screen. When it is closed, iPhone suspends it and nothing runs.You do not lose readings — the sensor keeps its own record and Vitality Tracker backfills it next time you open the app. But that record is one reading every fifteen minutes, which is an average. A sharp rise and fall after a meal can be almost invisible on a fifteen-minute average, and that spike is usually the thing you wanted to see.Android is different: turn on Keep collecting when closed and it keeps fetching every two minutes with the app shut. See how it works.

Alerts cannot be relied on

An alert can only be sent while Vitality Tracker’s own code is running. On iPhone that means the app is open. It also cannot override silent mode or a Focus.So an alert may arrive late, or not at all. Keep your sensor app’s own alarms switched on. Ours is for noticing patterns, not for catching emergencies.

If the app has not run for twelve hours, readings are lost

The backfill reaches back about twelve hours — that is a limit of what LibreLinkUp will hand over, not something we chose. Beyond that, the readings are gone from Vitality Tracker’s point of view, though they remain in your sensor’s own app.You will be told: two hours after the app stops syncing, a notification says “Syncing has paused”.

There is a delay of a few minutes, always

A CGM measures fluid under the skin, not blood, and that lags blood glucose by roughly five to fifteen minutes — more when your glucose is moving fast. Then the reading travels to Abbott’s servers and on to us.This is normal and true of every CGM. It matters most when you are changing quickly: during a rise after a meal, the number you see is a few minutes behind where you actually are.

Where everything lives in the app

Menu → Settings → CGM Integration is the single place all of this is set up and checked.

The CGM Integration section of Vitality Tracker settings — Settings → CGM Integration, with a Libre 2+ connected

Reading down that screen:

Libre 2+ connected — your LibreLinkUp account, and when readings last arrived
Ottai connection — credentials for a bridge app, if you use one
High / Low glucose alert — switches and thresholds
last check — what the alert rule decided most recently, in plain words
Freestyle Libre 2+ sensor — which day of its life the sensor is on
Shared with Apple Health — whether readings are being published
CGM data is present — whether anything is actually arriving

That last line is the one to look at first when something seems wrong. It asks the database rather than the settings, so it answers “is this working” rather than “is this configured” — and those are different questions.

Set up a Libre 2+

The full walkthrough, from buying the sensor to seeing your first reading

Set up another CGM

Ottai, xDrip, and anything Nightscout-compatible

Alerts

High, low, sensor warnings — and what they cannot promise

How it works

Density, sharing, sensor life, and fixing bad data

The idea

Your wearable