The Freestyle Libre 3 allows diabetes patients to manage their blood sugar level with the Freestyle Libre Link 3 App. The App is connected to an sensor on the arm of the patient. The glucose value is transmitted every minute via bluetooth and uploaded to the Freestyle Libre cloud.
Unfortunately there is no compatible smartwatch app for the FreeStyle Libre 3 App. But Freestyle Libre provides an App called LibreLinkeUp for parents or partners to controll the blood sugar level. After some reengineering i am able to read out the current blood sugar level and the graph data from the LibreLinkUp-API. I extracted the value and show it on Fitbit Smartwatches (as seen in the Screenshot). On the watchface the current steps, the heart frequence, the blood sugar level and the blood sugar trend arrow is shown.
The code is currently not open source, but i will publish it soon (if the code is not online yet, send me message). The app can be build locally uploaded as private app to the Fitbit app store and installed by the original Fitbit app.