Guardian Monitor is a glucose monitoring app for people with diabetes and for those watching over them — a parent following a child, or anyone keeping an eye on someone close to them.
It shows real-time glucose data, charts and markers, and keeps you informed through alarms, widgets, Live Activities and the Apple Watch. The alarms run on your own phone, so you are woken by your device rather than depending on someone else's.
Important: Guardian Monitor is a read-only client. It never changes any setting in the service it connects to. It is an informational application, not a medical device, and must not be used as a basis for treatment decisions.
Guardian Monitor works with Medtronic CareLink — Guardian, Simplera and MiniMed systems — and with Sibionics, where a GS3 sensor has been shared with you.
You choose the provider on the very first screen, before signing in. You can change it later by logging out and picking the other one.
First, choose your provider. Before any login screen appears, the app asks which service to read from — Medtronic CareLink or Sibionics. Pick one and you are taken to the matching sign-in form. If you land on the wrong one, the link at the bottom takes you back to the choice.
Medtronic CareLink. Enter the same login and password you use on the CareLink partner portal. Above the fields there is a Region selector with three options: Automatic detection, United States and Outside the US. Leave it on automatic unless sign-in fails, then set your region by hand — US accounts live on a different server from the rest of the world.
Sibionics. Enter the e-mail address and password of your Sibionics Companion account. Following someone else's sensor requires that person to share it with your account in their own Sibionics app first; until they do, the app will tell you the account is not following anyone yet.
The app shows one person at a time. If your account follows more than one, you pick which of them to display and switch between them in Preferences.
The current glucose level with a trend arrow and the time since the last reading, in large type meant to be read from across the room. Below it, a doughnut shows your time in range over the last 24 hours, and where the provider supplies it, the active insulin.
Tapping the reading switches to full screen, which enlarges it further and hides everything else — useful on a bedside table at night. Tap again to go back.
Coloured banners appear above the reading when the system has something to report: sensor disconnected, searching for signal, sensor initialisation or error, calibration required, insulin delivery suspended, no data transfer, and so on. They come from the connected system, not from the app.
Glucose readings over time with markers underneath them: insulin boluses, meals, auto-corrections, basal changes, notes, exercise and time changes. Tap any marker to open a card with the details — the exact amount, the time, and for a bolus that was interrupted, how much of the programmed dose was actually delivered.
Time span. Choose how much of the day is visible at once: 3 hours, 6 hours, 12 hours or a full day.
Another day. The calendar button opens a date picker and jumps the chart to that day. Leaving the app idle for a few minutes returns it to live data by itself, so you never come back to a stale chart.
Options. Three switches:
Statistics for a period you choose: 3 hours, 6 hours, 12 hours, 1 day, 3 days, a week, 2 weeks, a month, or a custom range with your own start and end dates.
For the chosen period you get time in range, average glucose, the number of readings against the number expected, and totals for insulin and carbohydrates with boluses and meals counted separately. Below that, a summary for each individual day in the range.
The thresholds come from your own settings, so the numbers reflect the targets you actually use rather than a generic range. Where treatment records only start part way into the period, the app says so rather than quietly showing a lower total.
Alarms run on your phone, from data the app fetches itself. They do not depend on the phone that wears the sensor. Everything below is off until you switch alarms on with the button at the top of the screen.
Limits. Two sliders, from 50 to 390 in steps of 5, in your chosen unit. An alarm sounds when glucose goes above the high limit or below the low one. These are separate from the range used for statistics, so you can be alerted at values wider than your target range.
Prediction. Warns before a limit is reached, based on the current trend. Set separately for the high and the low limit: never, or 5 to 30 minutes ahead in steps of 5.
Missed readings. An alarm when data stops arriving, from 10 to 45 minutes in steps of 5. This is often the first sign that something went wrong upstream — a lost sensor connection, or a phone that stopped uploading.
Sound. Pick from the built-in alarm sounds, set the volume from 0 to 100%, and choose a volume increase time — the alarm starts quietly and reaches full volume over 0 to 60 seconds, in steps of 10, so it wakes you without startling you. Vibration can be switched on separately.
Test alarm plays the alarm exactly as it would sound at night, so you can check the volume before you need it.
Snooze. Every alarm notification offers a full set of snooze durations. You can also silence an alarm from the Lock Screen and from the Live Activity, where the button uses the duration set in the Live Activity configuration.
For alarms to work when the app is not open, background mode has to be on. The app will tell you if it is not.
What the connected system reports about itself.
Sensor — whether it is online, how long it has left, its serial number and when it was started.
Pump, on systems that have one — battery level, reservoir level in percent and in units, and the infusion set timer where the pump tracks it.
Phone — the battery of the phone that uploads the data, since when that phone dies, everything else stops.
Each device shows a crossed-out cloud instead of its readings when the system reports no current data for it.
Your account, the person currently being followed, and a logout button. If the account follows several people, tapping the patient opens the list to switch between them; the app reloads the data for the person you pick.
Keeps the app alive when it is not on screen, which is what makes alarms and continuous updates possible. It works by playing a standby sound, which is how iOS allows an app to keep running.
The sound has its own volume slider, from 0 to 100%. Setting it to zero mutes it without switching background mode off — the app keeps running, you just do not hear it.
Shows the current glucose on the Lock Screen and in the Dynamic Island while the app runs in the background, mirrored to the Apple Watch and to CarPlay.
On iOS 17 and later the Live Activity also carries two buttons, each showing whether it is currently on: a bell that switches alarms on and off, and a speaker that switches voice reading on and off. When an alarm is sounding, the Live Activity shows its message and a snooze button, and afterwards displays the time until which it stays silenced. The buttons require a subscription.
A Configuration page underneath controls what the widget contains — including whether it shows a chart — and how long the snooze button on it silences an alarm. The snooze duration set here applies only to that button; the alarm notification itself always offers every duration.
Live Activities need Background App Refresh enabled in iOS settings. Without a subscription a session lasts 15 minutes; with one, 8 hours.
Writes your data into Apple Health, where other apps can read it. You choose which types to synchronise: glucose, insulin (basal, bolus and correction) and carbohydrates.
The data stays on your device. Guardian Monitor only writes to Apple Health and never reads from it. If permissions are missing, the app says which ones and links you straight to the right place in the Health app.
Uploads glucose readings and treatments to your own Nightscout server. You enter the URL and the Secret API Key, and the app verifies both before switching synchronisation on — a wrong key or an unreachable server is reported immediately rather than failing silently later.
Once running, the page shows the time of the last successful synchronisation. Synchronisation covers the person currently selected.
Shows whether a subscription is active and its renewal or expiry date, with buttons to change the plan, manage it in your Apple Account, and restore purchases after reinstalling or on a new device.
The two norms define your target range. They drive the colours on the home screen and the chart, and the time-in-range figure in statistics. They are deliberately separate from the alarm limits.
Register the Glucose Report shortcut and ask Siri for the latest reading. The app answers with the value, the unit and how long ago it was measured, in your device's language — useful while driving.
A full application, not just a complication: current glucose with trend, time in range, a chart, the list of recent markers and the same device status as on the phone.
Complications put the reading straight on the watch face and come in four shapes: corner, circular, inline and rectangular, so there is one for every face that accepts them.
Under Data Source on the watch you choose where it takes data from:
The widget gallery holds two separate entries.
For high resolutions (iPhone, iPad) is the everyday one, available in small, medium and large, plus extra large on iPad. On iOS 16 and later it also offers two Lock Screen sizes: rectangular and circular.
Dedicated for CarPlay is a single small widget whose content is laid out for the car dashboard rather than for a phone, so it stays readable at a glance while driving. Add this one only in CarPlay; on the phone the first widget looks better.
All of them show the current reading, the trend and time in range, and refresh along with the app.
While a Live Activity is running, the current reading appears on the CarPlay dashboard, so you can see it without touching the phone.
The app runs on iPad with a layout built for the larger screen: a sidebar with the sections instead of a tab bar at the bottom.
Most of the app is free. The subscription covers the features that keep working when you are not looking at the screen.
Free
With a subscription
A free trial is available, granted by Apple once per Apple Account. Subscriptions are monthly or quarterly, billed by Apple and managed in your Apple Account settings. If a subscription expires the app keeps working without the features above, and nothing is deleted.
Guardian Monitor can only show what the service you connect to actually reports.
Medtronic CareLink provides glucose readings together with insulin doses, meals, auto-corrections, pump status, the infusion set timer and the state of the phone uploading the data.
Sibionics is a sensor-only service. It reports glucose alone, so insulin and meal markers stay empty, the chart shows readings without treatment markers, statistics show no insulin or carbohydrate totals, and the pump section does not appear at all.
Guardian Monitor is an independent application. It is not affiliated with, endorsed by, or connected to Medtronic or Sibionics.