Common Stelo Biosensor Issues and How to Fix Them

If your Stelo Glucose Biosensor isn't working as expected, use this guide to troubleshoot the most common issues. For issues that require a replacement, follow the steps here: How to Get a Stelo Replacement.

🔗 Stelo won't pair

Your phone may show "Searching for sensor" when it can't find your Stelo. Pairing usually takes under 5 minutes.

⚠️ Step 1: Make sure you're using the right app.
This is the most common cause of pairing failure, especially for members who previously used a Dexcom G7. The Stelo Glucose Biosensor only works with the Stelo by Dexcom app. The Dexcom G7 app and all other Dexcom apps are not compatible with Stelo and will show a "pairing unsuccessful" error.

Step 2: Try these troubleshooting steps:

Turn Bluetooth off, wait 10 seconds, then turn it back on.
Close the Stelo app completely, then reopen it. Do not force-quit it and leave it closed.
Keep your phone within 20 feet of the biosensor — ideally on the same side of your body.
Confirm the pairing code you entered matches the code printed on your applicator (not the box).
Move at least 20 feet away from other people wearing biosensors — nearby devices can interfere with pairing.
Wave the applicator over the top of your sensor while it's on your arm (there is a tiny magnet in there that can sometimes kickstart the warm up process)
Note: each biosensor can only pair with one phone.

If pairing still fails after these steps, the biosensor may be defective. Contact our team for a replacement: How to Get a Stelo Replacement.

Learn more: Why is my device still searching for sensor? (Stelo Support)

📶 Sensor reconnecting

Sensor reconnecting happens when your phone stops receiving glucose readings from your Stelo for more than 15 minutes. When the connection resumes, up to 24 hours of missed readings can backfill automatically.

Try these quick fixes (give it up to 5 minutes):

Turn Bluetooth off, then back on.
Keep the Stelo app open on your screen — don't force-quit it.
Stay within 20 feet of your biosensor with a clear line of sight.
Keep your phone on the same side of your body as your biosensor.
Restart your phone if the above steps don't work.

Learn more: Why am I getting signal loss? (Stelo Support)

📊 No glucose data appearing in the Levels app

If the Stelo app is showing readings but nothing is appearing in Levels, this is almost always caused by a Dexcom User ID mismatch — meaning you signed into Levels with a different login method (email vs. phone number) than you used to create your Dexcom account.

Step 1: Find your Dexcom User ID in the Stelo app

Open the Stelo by Dexcom app.
Tap the gear icon → Account.
Look for which credential is labeled [User ID] — it will be either your email address or your mobile number.

Step 2: Reconnect in the Levels app using the matching login

Open the Levels app → More → Device Manager → Manage.
If you see an existing Dexcom/Stelo connection, tap Disconnect. If there's no disconnect option, skip to the next step.
Under Change Model, select Stelo Glucose Biosensor.
Tap Connect Dexcom Account and sign in using the same User ID method you found in Step 1:
- If your User ID is your email, sign in with your email.
- If your User ID is your mobile number, tap "use it to log in" or "Signed up with mobile number?" before signing in.
Agree to the Permission to Disclose and Authorization prompt.

Once reconnected, new glucose readings should appear in Levels within about 15 minutes. Note: Stelo records every 5 minutes, but Levels refreshes Stelo data on a 15-minute cadence — this is normal.

Also check:

Make sure the Stelo app is running in the background on your phone. You don't need to have it open, but don't force-quit it — this can interrupt data flow to Levels.
If you're not seeing data in the Stelo app at all, go back to the Stelo won't pair section above first.

⏰ Session ended early

The Stelo app shows "Session ended early" when the biosensor can no longer read glucose and ends before the full 15 days.

To get a replacement, reach out to our team following the instructions here: How to Get a Stelo Replacement.

Tips to help prevent early session endings on future biosensors:

Keep the Performance Cover dry for the first 12 hours after applying if possible.
Pat the Performance Cover dry gently after it gets wet — don't rub.
Avoid placing the biosensor in areas that frequently get bumped, pressed, or compressed while you sleep.

Learn more: What does "session ended early" mean? (Stelo Support)

📏 Readings seem inaccurate or don't match finger sticks

This is one of the most common questions we hear. Here's what's normal, and what's not.

Why Stelo and finger stick readings can differ:

Stelo measures glucose in your interstitial fluid (fluid between your cells), while a finger stick measures glucose directly from your blood. Because of this, there's typically a 10–15 minute lag between the two — most noticeable when your glucose is rising or falling quickly (e.g., after a meal or during exercise).
Even when glucose is stable, Stelo is designed to be within 20% of a lab result for readings above 70 mg/dL. For example, if a finger stick shows 100 mg/dL, a Stelo reading between 80–120 mg/dL is considered within spec.
Stelo cannot be manually calibrated — it's factory-calibrated by Dexcom.

When to focus on trends vs. individual numbers:
At Levels, we recommend using your glucose trends — how your levels respond to meals, activity, and sleep — rather than fixating on exact readings. A consistent pattern is more meaningful than any single number.

When to report it as a hardware issue:
If your sensor is consistently 30+ mg/dL off for multiple days in a stable state (not during rapid glucose changes), that falls outside the expected range and may indicate a faulty sensor. In that case, it's worth reporting to our team for review.

Note on the display range:
Stelo is designed for general wellness use and only displays readings between 70–250 mg/dL. If your glucose falls outside that range, the app will show <70mg/dL rather than an exact number. This can sometimes make readings appear more inaccurate or erratic than they actually are — especially if you're comparing against a finger stick that shows a specific value outside that window. You can always view your full glucose range on Dexcom Clarity.