I recently tried a Continuous Glucose Monitor and wore it for 15 days. It was a FreeStyle Libre 3. I was trying it for fun; to learn more about myself and how productive my body's insulin response is.
The insertion process wasn't too painful, but it is inserting a small needle into your arm. I inserted mine a bit above the midway point between my shoulder and elbow, so it was covered by a t-shirt. The sensor has an adhesive that kept it on reliably for the 15 day period. I showered and exercised normally.
The device is low-power bluetooth and disposable. It's paired over NFC, which felt futuristic (holding my phone to the back of my arm). You pair the device with an app, but you need to use a different app if you want historical data. This means both need to be installed. You cannot export the data - no CSV, no HealthKit.
I was happy to learn that my body has a great insulin response to glucose. I noticed that even after having some thing really sugary, my body responded quickly and recovered my glucose levels by administering insulin. Here's an overlapping day graph (midnight to midnight) for the sensor duration. You can see I was able to maintain my glucose within healthy levels:
I recommend trying one of these sensors! A note if you want to try for yourself: Unfortunately, a monitor like this is supposed to be prescribed by a doctor.