Libre says “No Data” (or connects but never shows readings)

CGM & sensors · Updated 2026-07-01

Sugalarm reads Libre glucose through Abbott's LibreLinkUp service — the same way a family member "follows" your sensor. It can only ever see what LibreLinkUp shows. So when Sugalarm says No Data, the fix is almost always in how sharing is set up, not in Sugalarm.

The #1 cause: you connected with your main LibreLink app login, but no sensor is actually shared to a LibreLinkUp follower account yet. Sugalarm connects as a follower — if nothing is shared to that follower, there's nothing to read.

1. Use a LibreLinkUp (follower) account — not your main LibreLink login

There are two different Abbott apps:

LibreLink — the app on the phone that runs the sensor (this is the patient).
LibreLinkUp — the "follower" app for caregivers. This is the account Sugalarm uses.

Give Sugalarm the LibreLinkUp email and password, not the LibreLink one.

2. Share the sensor to that follower account

In the LibreLink app (the one running the sensor): open the menu → Connected Apps → LibreLinkUp.
Add / invite the caregiver by the email of the LibreLinkUp follower account you gave Sugalarm.
Open the LibreLinkUp app (or check its email) and accept the invitation. Sharing isn't active until the invite is accepted.

3. Reconnect in Sugalarm

After sharing is accepted, in Sugalarm go to Settings → CGM & Connection → reconnect Libre with the follower credentials. Readings usually appear within a few minutes.

If Sugalarm showed an amber "Almost there — no sensor is shared to this account yet" note when you connected, that is exactly this problem: the login worked, but no sensor is shared to it.

4. Check the basics on the sensor side

Is the LibreLink app itself showing a current reading? If LibreLink shows No Data, Sugalarm will too — fix the sensor first.
New sensor warm-up: a just-applied sensor has about a 1-hour warm-up with no readings. Wait it out.
Phone online: the LibreLink phone has to upload to Abbott's cloud — if that phone is offline, the cloud (and Sugalarm) goes stale.

5. Give it a couple of minutes

LibreLinkUp lags the sensor slightly, and Sugalarm polls on a short cycle. A fresh connection or a sensor that just came online can take a few minutes to show its first reading. Persistent No Data after ~10 minutes with a healthy sensor points back to the sharing setup (steps 1–3).

Quick summary: Sugalarm needs the LibreLinkUp follower login, and that follower must have a sensor shared and accepted. Get those two right and No Data clears on the next reading.