There’s a startup named Movano Health trying to build a glucose monitor sensor chip that uses RF energy:

https://www.wareable.com/wearable-tech/movano-ceo-on-its-rf-...

Movano plans to ship an Oura-style smart ring this year, but it won’t have the glucose monitor. (One might suspect the “moonshot” glucose RF chip story is meant to keep investors excited through the zero-revenue stage until hopefully the more ordinary smart ring takes off.)