The way (these) continuous glucose monitors work is that there's an adhesive patch with the needle, sensor, some storage/processing and comms module. Attaching

The way (these) continuous glucose monitors work is that there's an adhesive patch with the needle, sensor, some storage/processing and comms module. Attaching the patch is done via a spring-loaded module and the data is read by waving the reading over the patch. The patch itself lasts a couple of weeks before it deactivates itself and you need to apply a new one. The patch/sensor doesn't hurt going in but depending on where it's attached and how you move it can sometimes pinch a bit when you move around. And you'll definitely feel it when you jostle it.