Why do users need to scan if the system uses Bluetooth?

The FreeStyle Libre 2 system is the FreeStyle Libre system with optional glucose alarms. Like the FreeStyle Libre system, to get a glucose reading users must scan the Sensor. They can take as many glucose readings as they want while wearing the Sensor. To get a 24-hour glycaemic picture, users must scan at least once every 8 hours.

The FreeStyle Libre 2 sensor sends information to the Reader or the FreeStyle LibreLink app every minute. The Reader and app use the information to determine if an alarm should be presented. To get a glucose reading the sensor must be scanned by the Reader or phone app.