I'm not sure if you're trolling, but glucose sensors are (minimally) invasive - they insert a filament under your skin with a needle.
I was surprised by GP's comment because to my knowledge there doesn't exist a device of this type which wouldn't require puncturing the skin.
My mom gets bombarded with ads selling non-invasive glucose monitors but the most plausible unit I have found uses lasers and has the size of a refrigerator, still in development.