In general, biosensors are not restricted on planes. As per regulations, flight crews might decide they don’t want electronic devices turned on during a flight, in which case, simply turn off your phone to stop it from scanning your biosensor.
You’ll still be able to access your data in flight mode. But while Bluetooth is disconnected, your biosensor will stop streaming your glucose data to your app. Instead, it will store it and stream it again when Bluetooth is connected.