Dexcom Icons, Alerts, and Symbols: What Do They Mean?

Brief or temporary Sensor Error / Issue

A Brief sensor error or brief sensor issue message means that your sensor is currently unable to measure the glucose in the interstitial fluid . This can happen at any time during the sensor life and usually fixes itself within 3 hours. Do not remove the sensor. Use your blood glucose meter for treatment decisions. If the issue persists for more than 3 hours contact Dexcom technical support*

No Readings Alert

The “No Readings” alert means the sensor is temporarily unable to measure glucose due to something blocking the sensor’s Bluetooth connection. Common causes of the No Readings alert include:

• If water is between your transmitter and display device • If your receiving device is out of range • If there is an obstacle in between you and your receiving device (such as walls or metal) • If you are laying on your sensor while sleeping

Ensure your sensor and display device* are close to one another and that nothing is blocking their connection. Wait 10 minutes to see if your Dexcom Continuous Glucose Monitoring (CGM) System begins displaying readings. If the issue persists, contact Dexcom technical support*

Sensor Failed Alert

A “Sensor Failed” alert means your Dexcom sensor is no longer able to provide reliable glucose readings.

What to do: • Remove the failed sensor and transmitter (if applicable). • Insert a new sensor following the instructions in the app or receiver. • Start a new sensor session in your Dexcom app or receiver. • If the issue persists or you receive repeated sensor failures, contact Dexcom Technical Support for further assistance and possible replacement. (see below for contact information)

Blood Drop Icon

The blood drop icon on your Dexcom display means a blood glucose (BG) meter value is needed. This may appear if your system requires a calibration, or if you’re using a sensor without a code. Follow the on-screen instructions to enter a fingerstick BG value, and always use clean, dry hands for accuracy.

Bluetooth is Off Alert

This alert means Bluetooth is turned off on your smartphone or receiver, so your Dexcom system cannot send or receive glucose data. Turn Bluetooth back on in your device settings to restore communication and ensure you continue to receive real-time readings and alerts.

Calibration Error

A calibration error occurs when the BG value you entered is outside the expected range or doesn’t match the sensor’s readings. Double-check your fingerstick technique and ensure your hands are clean. If the error persists, follow the on-screen instructions - usually, you’ll be prompted to enter a new BG value within a set time.

Hourglass Icon

The hourglass icon indicates your sensor is in the warm-up period or that a process is underway (such as starting a new sensor session). During this time, you won’t receive glucose readings or alerts. Wait until the warm-up is complete; your Dexcom app or receiver will notify you when your sensor is ready.

Pairing Unsuccessful

If you see a “Pairing Unsuccessful” message, your CGM and display device (app or receiver) did not connect. If your CGM device has a separate transmitter, make sure it is correctly installed into the sensor housing. Check that the Bluetooth is switched on and your device is within range of the sensor. Retry pairing as instructed. If the problem continues, restart your device and try again.

Signal Loss Alert

A signal loss alert means your display device (phone or receiver) has temporarily lost communication with your Dexcom sensor. This can happen if you move too far away, there are obstacles (like walls or water), or Bluetooth is turned off. Move your receiving device closer to the Dexcom sensor and ensure Bluetooth is enabled. If the signal isn’t restored within a few minutes, follow the troubleshooting steps in your user guide, check out our Reducing signal loss FAQ or contact our technical support team. (see below for contact information).

Question Marks (??)

If you see question marks instead of a glucose value, your Dexcom system is temporarily unable to provide a reading. This can occur if the sensor is adjusting, there’s interference, or the system needs more data. Wait up to 3 hours; if the issue persists, replace the sensor as instructed.

Orange Phone Icon on Apple Watch

The orange phone icon on your Apple Watch Dexcom app means your watch is temporarily not receiving data directly from the sensor and is instead relying on your iPhone for updates. Keep your phone nearby and ensure both devices have Bluetooth and internet enabled. The icon will disappear when direct communication is restored.

If you experience any of the issues above and this guide does not help you to resolve the issue please contact our technical support team for further help.

*Fill in our online form https://dexcom-intl.custhelp.com/app/support_request or call UK- 0800 031 5763 / Ireland 1800827603