SugarSentry
SugarSentry User Manual
Last updated: October 7, 2026
SugarSentry shows the glucose, trend, insulin and pump status from a Medtronic CareLink account, and alerts you, with sound, when the pump reports an alert or when new readings stop arriving. This page covers getting connected, what you can set, every symbol and colour on screen, and every alert: where it comes from, how it sounds and how to answer it.
Getting started
- Install SugarSentry from the App Store and open it.
- Pick your CareLink region and log in with the CareLink care-partner account that follows the person you look after. SugarSentry then checks that account about every 5 minutes, in step with the sensor.
- Allow notifications and Critical Alerts when iOS asks. Notifications are what let an alert reach you with the phone locked or the app closed; Critical Alerts let the important ones sound through silent mode and Do Not Disturb.
- Leave Background Sync on. It turns on by itself after login and lets our server watch the account while the app is closed.
- More than one person? Add each one in Settings with their own CareLink login, a name and a colour.
- Optional: add the Apple Watch complication, connect CarPlay, share a web link, or ask Siri "what's my glucose?".
What you can set
All of these are in the app's Settings, per person where noted:
- Display unit (per person) - mmol/L or mg/dL, used everywhere in the app and on the web link.
- Low and high range (per person, 4.0 and 10.0 mmol/L until you change them) - colours the glucose shield and chart, drives Time in Range, and decides whether a snoozed Low or High rings again when its snooze ends (see Snooze). Which alerts the pump raises in the first place still follows the pump's own low and high settings.
- Alarm sound (per person) - Two-Tone, Triple Chirp or Siren, so you can tell whose alert is ringing without looking. The web link plays the same sound.
- Test Alarm - rings the alarm screen with your sound for up to a minute, in blue (real alerts are red, orange or grey). Lock the phone or leave the app to check it keeps sounding; End Test stops it. Nothing is sent anywhere.
- Override Silent Mode - Critical Alerts, on by default. See Critical Alerts.
- Background Offline Check - on by default. Alerts you when this phone hasn't synced for an hour or more while the app is in the background, for example after losing internet. Because iOS decides when apps may run in the background, it can also ring when the connection is fine, so it can be switched off. Turning it off does not change the status strip.
- Silence All Alerts (per person) - see Silence All Alerts.
- Show on Lock Screen - the Live Activity on the Lock Screen, Dynamic Island and CarPlay.
- Appearance - nine looks for the app on this phone. Alerts, glucose colours and person colours never change with it.
- Name and colour per person, used on the Overview, in alerts and on the Lock Screen once more than one person is added.
- Web link - create, share or replace a read-only link.
Which alerts exist, and when the pump raises them, come from the pump and CareLink and are set on the pump. Snooze is 15 minutes, or 30 for High Glucose, and is not adjustable.
Features
Monitoring runs on our server, not your phone
With Background Sync on, SugarSentry's server checks CareLink around the clock, whether your phone is open, locked or in a pocket. Alerts still arrive if the app hasn't been opened in days, and the phone spends no battery doing the checking.
Alerts you won't miss
With the phone locked or the app closed, an alert arrives as a notification with sound and keeps coming until you snooze it, dismiss it or open the app. While the app is open, it takes over the screen with sound. Details in How an alert reaches you.
More than one person
Follow two or three people from one phone. Each has their own CareLink login, name, colour, range, alarm sound, alerts and Silence switch. Snoozing one person's alert never touches anyone else's.
Silence All Alerts vs. Snooze
Snooze answers one alert that is ringing now, for 15 minutes (30 for High Glucose), and it comes back if the problem is still there. Silence All Alerts is a per-person switch in Settings that stops that person's alerts until you turn it back off - for when you truly can't respond.
A web link you share yourself
Each person can have a random web link that cannot be guessed. SugarSentry never sends it anywhere: you copy it and send it yourself, to a grandparent, a school nurse or a doctor. It opens a read-only live dashboard in any browser, with no app and no login, and can ring along with alerts. Nothing done there can silence an alert on your phone. Create a new link and the old one stops working at once.
Lock Screen, CarPlay, Apple Watch and Siri
The latest reading on the Lock Screen and in the Dynamic Island, on the CarPlay dashboard while you drive, on the Apple Watch, and from Siri. For a Shortcuts automation that opens the app to keep it current, use the Keep SugarSentry Current action instead of Open App: an alert on screen then keeps its sound, because nobody is actually looking.
Reading the screen: every symbol and colour
The colours that never change
Whatever look you pick, the meaning of a colour stays the same:
| Colour | On the glucose, the chart and the Lock Screen |
|---|---|
| Green | In your range. A reading exactly on a limit counts as in range. |
| Orange | Above your high limit. |
| Red | Below your low limit, below the sensor's floor, or the sensor needs action (Change Sensor, Sensor Updating). |
| Blue | Sensor warming up: no readings yet. |
| Grey | No current reading: the last one is 15 minutes old or more, or none has arrived. |
The alarm screen uses its own colours, by how urgent an alert is rather than by direction; see Alarm screen colours. The Night Ward look softens the shield's colours for the dark, but keeps their meaning. The Black look turns the chart's range band and limit lines grey, but never the glucose itself.
Header
- Log Out on the left, the person's name in the middle, the gear for Settings on the right. The gear turns red when the server needs you to log in to CareLink again.
- With two or more people: a people icon that opens the Overview, a dot in the person's colour, and the header tinted with that colour.
- Now or N min ago with a circular arrow: when the app last refreshed. Tap to refresh now. This is not the age of the reading; that is on the shield.
Status strip: Phone, Backend, Sensor
The thin strip under the header answers "will an alert reach me?". Each dot is the worst of the checks under it. On the right it says Covered when everything passes, or names the worst problem, for example "Critical alerts: Off". Tap it for the full list, with a Fix button where there is something to fix.
| Dot | Meaning |
|---|---|
| Green | Every check passes. |
| Orange | Alerts arrive, but not as set up (for example Critical Alerts off or Silence All on), or a known gap is in progress, such as a sensor warm-up. |
| Red | An alert could not reach this phone right now. |
| Grey | Can't be known from this phone, for example while it is offline. |
- Phone: Internet, Notifications, Critical alerts, Silence all alerts, Background App Refresh, and when iOS last woke the app.
- Backend: paired with the server, the CareLink login still valid, the server can push to this phone, and its last successful check.
- Sensor: sensor state (OK, warm-up with time left, searching for signal, Change Sensor, Sensor Updating), age of the last reading (red after 15 minutes), sensor life left (orange under a day), and the pump connection.
The glucose shield
The big shield is the current reading. Its colour follows the table above; the number, the unit and the age sit inside it. When a new reading lands, the shield glows once (not with Reduce Motion on).
| You see | It means |
|---|---|
| A number, an arrow, the unit, "Just now" or "N min ago" | The latest reading and how old it is. |
| -- with the age in red | The last reading is 15 minutes old or more. The number is hidden on purpose, so an old value is never mistaken for a current one. |
| BELOW 2.8 (or 50 mg/dL), red | Glucose is below the lowest value the sensor can measure. Treat as an urgent low. |
| WARM UP, blue, with time left | A new sensor is warming up; readings start when it finishes, about 2 hours. |
| CHANGE SENSOR or SENSOR UPDATING, red | The pump reports the sensor needs replacing, or is updating and sends no readings meanwhile (up to 3 hours). |
| Purple outline, no fill | The pump is in Safe Basal. |
| No shield shape around the number | The pump's Auto Mode (SmartGuard) is off. |
| A grey shield with a time | You are inspecting a point on the chart; double-tap the chart to return. |
Trend arrows
The arrow is CareLink's own trend for the latest reading:
| Arrow | Meaning |
|---|---|
| ↑ ↑↑ ↑↑↑ | Rising, rising quickly, rising very quickly |
| ↓ ↓↓ ↓↓↓ | Falling, falling quickly, falling very quickly |
| No arrow (→ on the Lock Screen and watch) | Steady, or no trend reported |
| ⇈ ⇊ | In the compact Dynamic Island, and when inspecting the chart: rising or falling quickly |
Next to the shield
- +0.3 or -0.2: the change since the previous reading, in your unit.
- Active Insulin: insulin still working, in units, as the pump reports it.
- LOWIN RANGEHIGH in the shield's colour.
- ⏸ SUSPENDED in red: the pump has stopped insulin delivery.
- SPORTS MODE in cyan, with time left: a temporary target is set on the pump.
- Yellow ⚠ ... pills for the pump's and sensor's own status: Calibration Required, Calibrating, Searching for Signal, Updating, Reconnecting to Pump, Sensor Off, Do Not Calibrate, Bluetooth Off, Pump Pairing Lost, No Data From Pump.
- as of HH:MM: the clock time of the last reading.
The chart
- Pinch to show from 1 to 24 hours (3 to start), drag to move back in time, double-tap to inspect a point.
- The green band is your range, with the orange line at your high limit and the red line at your low limit.
- The glucose line turns orange above your range and red below it. It breaks where readings were missing for more than 15 minutes. The dot at the end is the latest reading.
- The band hanging from the top is basal insulin, taller for a higher rate.
| Marker | Meaning |
|---|---|
| Small vial, blue | A bolus. Tap for the amount, and the meal entered with it. |
| Short blue bar in the basal band | An automatic correction by the pump, longer for a bigger dose. |
| Fork and knife, amber | A meal, with its carbs. |
| Teardrop outline, red | A calibration; its tip sits at the blood glucose entered. |
Cards
Bars turn orange under 40% and red under 20%. -- means the value isn't known right now.
| Card | Shows |
|---|---|
| Sensor Life | Time left on the sensor and how long it has been in. Orange under 2 days, red under 1. |
| Reservoir | Percent and units left, and how long since the reservoir was changed (counted from when SugarSentry first saw it). |
| Pump Battery | The pump's battery. |
| Phone Battery | The phone that uploads to CareLink, usually the child's phone - not your phone. |
| Sensor Battery | The sensor's transmitter. |
| Time in Range | CareLink's own figure. |
| Average Glucose | CareLink's own figure. |
| Sensor Status | ALL GOOD, or the sensor's state. Red for Change Sensor or Sensor Updating, orange for anything else unusual. |
| Pump Mode | Auto Basal, Safe Basal or Feature Off; Suspended; or Sports Mode with time left. |
| Device | Pump model and serial number. |
Last 24 hours totals bolus, basal and carbs, counts alerts (red when any; tap to list them), and gives Time in Range and average glucose worked out from your own range, so it can differ from CareLink's card. The Events report lists the pump's events, newest first, each with a coloured dot: blue for insulin, amber for meals, red for calibrations, suspends and sensor alerts, purple for pump alerts, orange for SugarSentry's own errors. "ALERT:" marks an alert, "INFO:" a status change.
Overview (two or more people)
Tap the people icon in the header. One card per person, framed in their colour: a small shield with the reading (or "--"), the change, active insulin, a range pill, the three status dots, and five small bars - SEN LIFE (sensor life), PHONE (the uploading phone's battery), PUMP (pump battery), SEN BATT (sensor battery) and RESV (reservoir) - with a line of the last hour in the person's colour. The time turns orange with a warning sign when that person hasn't refreshed for 15 minutes or more; "Needs login" means their CareLink login has expired. Tap a card to switch to that person.
Lock Screen, Dynamic Island and CarPlay
The Live Activity is a display only: it never sounds an alarm.
- Lock Screen and CarPlay: the person's colour dot and name, the age of the reading, the reading in its range colour with arrow and unit, and the change and active insulin. The background is tinted dark green, amber or red with the range.
- Dynamic Island: the reading and arrow on the left, the change on the right; pressed open, the same as the Lock Screen.
- -- in grey with the age in red: no new reading for 15 minutes.
- WARM UP in blue, or an hourglass in the compact Island: sensor warming up.
- SENSOR UPDATING in red, or circular arrows in the compact Island.
- Below 2.8, or <2.8 in the compact Island: below the sensor's floor.
iOS ends a Live Activity after 8 hours; SugarSentry replaces it before then. If it ever looks frozen, open the app.
Apple Watch
- The watch app shows one page per person (swipe between them): the reading and arrow on a background in its range colour, a line of the last hour, the change and active insulin. After 15 minutes the number becomes "--" with the age in red. It updates when you open it and with Refresh.
- In place of a number it says why: below 2.8 (urgent low), warming up, sensor updating, login expired, or no recent reading.
- The complication shows the first person: the reading and arrow in range colour; blue "--" during warm-up; red circular arrows for Sensor Updating; red "<2.8" below the floor; an orange "!" when it couldn't get a reading.
The complication does not switch to "--" when its reading is old: watchOS decides when it refreshes, and until then it keeps the last number, in colour. Check the age on the rectangular one, or open the watch app, before relying on it.
The web link
A read-only copy of the dashboard in a browser, updating every 30 seconds: the shield, pills, chart (scroll sideways, tap a point to inspect), cards, events and last 24 hours, in the same colours and with the same nine looks as the app, picked with the palette button and kept per browser. How it rings is under Alerts in the browser.
Person colours
With more than one person, each gets a colour from a set chosen to stay distinct for colour-blind eyes: Orange, Sky Blue, Bluish Green, Yellow, Blue, Vermillion, Reddish Purple and White. It shows on the Overview, the header, the Lock Screen and the alarm screen.
Looks
| Look | |
|---|---|
| Classic | The original: black with a teal header, modelled on the CareLink app. The default. |
| Light | Clean and bright, white cards. |
| Dark | Deep charcoal with purple. |
| Soft | Gentle pastels, rounded. |
| Aurora | Midnight to teal to violet. |
| Night Ward | For the 3 a.m. glance: near-black, dim amber, a larger number and softened colours. |
| Graph Paper | Ink and grid, nothing else. |
| Playground | Bright and rounded, for the child holding the phone. |
| Black | Greyscale everywhere except the glucose. |
Alerts: what you get, and from where
SugarSentry's alerts come from two places:
- The pump, through CareLink. Every alert the pump raises and uploads to CareLink - glucose, insulin delivery, sensor, battery, reservoir - is passed on with its own name. Which ones the pump raises, and at what glucose levels, is set on the pump.
- SugarSentry's own checks, which CareLink doesn't have: no new readings, the server losing CareLink, a login that expired, and anything that would stop an alert reaching your phone.
Alarm screen colours
| Colour | Used for |
|---|---|
| Red | Act now: lows, High Glucose, stopped insulin delivery, pump errors, lost sensor signal, Change Sensor, Sensor Updating, an empty reservoir or a dead pump battery, and every check that means you may not be getting alerts. |
| Orange | Heads-up: early warnings, BG checks and calibrations, reservoir and battery running low, reminders. |
| Grey | No readings, monitoring interrupted, and the set change reminder. |
| Blue | Test Alarm only. |
In the tables, Silent mode: Yes marks a Critical Alert: it sounds through silent mode and Do Not Disturb while Override Silent Mode is on. Every other alert is Time Sensitive: it can get through a Focus mode and plays your sound, but not on silent.
Low glucose
| Alert | Colour | Silent mode |
|---|---|---|
| Urgent Low Glucose | Red | Yes |
| Low Glucose | Red | Yes |
| Alert Before Low | Orange | - |
| Low Sensor Glucose. Check BG | Red | - |
| Suspend On Low / Suspend Before Low. Delivery Stopped. Check BG | Red | - |
| Basal Delivery Resumed. Check BG, and the other "Basal Resumed" alerts | Orange | - |
High glucose
| Alert | Colour | Silent mode |
|---|---|---|
| High Glucose (Snooze is 30 minutes) | Red | - |
| Alert Before High | Orange | - |
| High Sensor Glucose For Over 1 Hour | Orange | - |
| SG Rising Rapidly | Orange | - |
| Correction Bolus Recommended | Orange | - |
Insulin delivery and the pump
| Alert | Colour | Silent mode |
|---|---|---|
| Insulin Delivery Stopped; Pump Error. Delivery Stopped; Critical Pump Error. Stop Pump Use; Pump Motor, Button, Settings or Power Error; Pump Restarted; Auto Suspend Limit Reached; Delivery Suspended. Connect Infusion Set; Rewind Required | Red | Yes |
| Call Emergency Assistance | Red | Yes |
| Bolus Stopped; Bolus Delivery Timed Out; Delivery Limit Exceeded; Minimum or Maximum Delivery Timeout. BG Required | Red | - |
| Enter BG for SmartGuard; Auto Mode Exit. BG Required | Orange | Yes |
| BG Check Reminder; Missed Meal Bolus Reminder; Active Insulin Cleared | Orange | - |
| Set Change Reminder (once, with Dismiss) | Grey | - |
Sensor
| Alert | Colour | Silent mode |
|---|---|---|
| Change Sensor | Red | Yes |
| Sensor Updating (with Dismiss) | Red | Yes |
| Lost Sensor Signal; Lost Sensor Signal. Check Transmitter; No Sensor Signal | Red | Yes |
| Sensor Expired. Change Sensor; Calibrate Now; Calibration Required | Orange | Yes |
| Calibration Error; Calibration Reminder; Silenced Sensor Alert; Recharge Transmitter Now or Soon | Orange | - |
| Sensor Connected | No alarm: a quiet entry in Notification Center. | |
Change Sensor and Sensor Updating also come from the sensor's own state, not just the pump's alert. Either has to last 2 minutes before it rings, so a passing blip doesn't wake you. "No data from pump" never rings by itself; if readings stop, the no-readings check covers it.
Reservoir and pump battery
| Alert | Colour | Silent mode |
|---|---|---|
| Reservoir Empty. Change Reservoir Now | Red | Yes |
| Pump Battery Out Limit; Pump Battery Removed | Red | - |
| Reservoir Low; No Reservoir Detected; Loading Incomplete; Replace Pump Battery Now or Soon; Pump Battery Not Compatible; Insert A New AA Battery | Orange | - |
Other pump alerts
A pump alert SugarSentry has no name for still reaches you, as a quiet Pump Alert notification with the pump's fault number. A pump alert that is more than 15 minutes old by the time it arrives comes as a quiet Earlier Pump Alert with the time it happened, so a late upload doesn't ring for something already handled - unless it is old only because you snoozed it, in which case it rings again. On a new install, alerts already cleared on the pump are recorded silently; ones still active ring.
SugarSentry's own checks
| Alert | When | Colour | Silent mode |
|---|---|---|---|
| 15 Minute Staleness Sentry (no new readings) | No new reading for 15 minutes, confirmed for 2 more. Not during warm-up or while the sensor searches for signal. From the server when the app is closed, from the phone when it is open. | Grey | Yes |
| Monitoring Interrupted | The server hasn't reached CareLink for 30 minutes. | Grey | Yes |
| Log In Again | CareLink refused the saved login. Repeats every 6 hours until you log in; has a Reconnect button. | Red | Yes |
| Background Sync Is Off | This person isn't connected to the server, so nothing watches while the app is closed. | Red | Yes |
| Alerts Can't Reach This Phone | For 10 minutes the server has had no way to push to this phone. | Red | Yes |
| Foreground Offline Check | The app is open and this phone has had no internet for 15 minutes. | Red | Yes |
| Background Offline Check | The phone hasn't synced for an hour, or longer if iOS usually leaves it longer (at most 6 hours), for example after losing internet with the app in the background. iOS decides when apps may run, so it can also ring when the connection is fine; answered with Got it. On by default; can be switched off in Settings > Alerts. | Red | Yes |
| Test Alarm | Only when you press it in Settings. | Blue | - |
How an alert reaches you, and how to answer it
With the phone locked or the app closed
- The server sends the alert as a push notification and repeats it every 5 seconds, each one replacing the last, for up to 20 minutes - until you snooze or dismiss it, or open the app.
- The phone schedules its own reminders too, up to 6, 5 minutes apart, so an alert still comes if the network drops.
- Press and hold the notification for Snooze, or tap it to open the alarm screen.
With the app open
- The alarm screen covers everything, in the alert's colour, with a ringing bell, the alert's name and your alarm sound on a loop. It plays through the silent switch while the app is open, and starts again after a call or Siri.
- With two or more people, it shows whose alert it is, with their colour.
- If you open the app yourself for an alert you have already heard, it comes up without sound. Leave it untouched for 60 seconds and the sound starts.
Snooze, Dismiss and Got it
- Snooze quiets that person's ringing alerts for 15 minutes (30 for High Glucose) on this phone and the server, and clears their notifications. If the problem is still there afterwards, it rings again. For a Low or High that means glucose still outside your low and high limits; an Urgent Low always rings again. An alert that wasn't ringing yet, such as a low turning into an urgent low, still rings.
- Dismiss is for alerts that don't need to come back: Set Change Reminder, and Sensor Updating, where one Dismiss covers the whole update (and keeps the no-readings check quiet for it). The next update alerts again.
- Got it answers the Background Offline Check; End Test ends a test.
- Reconnect, on Log In Again, takes you straight to the CareLink login.
A snooze is shared by every phone following the same CareLink account: snoozing on one quiets the server's repeats for the others too.
Several alerts at once
One alert shows at a time and the rest wait their turn; the waiting ones arrive as quiet banners. Urgent Low, Call Emergency Assistance, Critical Pump Error, Log In Again and the checks that mean you may be unmonitored go to the front of the line. With more than one person added, alert titles start with the person's name ("Emma: Low Glucose").
Critical Alerts (Override Silent Mode)
On by default. The alerts marked "Silent mode: Yes" then sound at full volume even with the phone on silent or in Do Not Disturb. Turning it off does not silence them: they still arrive, play your sound and open the alarm screen, but no longer override the ringer switch. If iOS has blocked Critical Alerts, the status strip says so.
Silence All Alerts
Per person, behind a confirmation. It stops that person's alerts on this phone and on the server, clears any waiting, and alerts raised while it is on are not saved up for later. Two still come through from the server: Log In Again and Monitoring Interrupted, because either means nobody is watching. The status strip turns orange while it is on.
Alerts in the browser
An open web link checks every 5 seconds whether the server is ringing an alert for that person. If it is, the page plays the same alarm sound, shows a red banner and flashes the tab's title, and shows a notification if you allowed it. Press Enable alerts once on that browser so sound and notifications are allowed. Dismiss there quiets only that browser: the phone keeps ringing. A closed tab gets nothing.
If something's not working
- Not getting alerts?
- Look at the status strip first: anything not green is named there, with a Fix button. Then check Settings > Notifications > SugarSentry (allow notifications, Critical Alerts and Time Sensitive) and Settings > General > Background App Refresh.
- The shield shows "--"?
- No new reading has reached CareLink for 15 minutes. Check that the child's phone is on, online and near the pump. The no-readings alert rings a couple of minutes later if it continues.
- Lost access to a person's data?
- Their CareLink login has usually expired. Open the app, go to that person, and log in again.
- SugarSentry isn't showing up in CarPlay?
- Check iPhone Settings > General > CarPlay > your car, and that Show on Lock Screen is on in SugarSentry.