In the past, monitoring glucose levels in people with diabetes required taking blood samples with a prick to the finger and using a reader to get a result.
Nowadays, continuous glucose monitoring (CGM) is available and involves a one-off prick to insert a tiny catheter under the skin in the arm which is connected to an adhesive-backed module that stays in place for two weeks.
Foregoing the finger-prick method is appealing but the accompanying waste and expense of such a short-term commitment has led to people taking them apart to see if they can be tweaked.
Thanks to [Andy Kong], we now know what’s inside the [Stelo CGM].
It has a coin cell to power an nRF52832 microcontroller which wakes up every 30 seconds to poll the sensor and every five minutes to send data via Bluetooth to the user’s phone, as well as antennas for Bluetooth and NFC.
There are also a few custom chips whose function is a mystery.
