A pain-free blood glucose sensor is being trialed by a UK-based company called Afon Technology. While there are supposedly various non-invasive hardware solutions being worked on, the Afon blood sugar level monitor comes as a supplementary device that people with diabetes can connect with their existing smartphone or smartwatch.
https://www.notebookcheck.net/Pain-free-non-invasive-blood-sugar-monitor-for-use-with-any-compatible-smart-device-in-the-Afon-pipeline.581938.0.html