Incidentally, I created something related to this yesterday. A tmux plugin to display your glucose data as a status icon in your terminal.
As a T1 myself, I use a Dexcom as my CGM and have it working around that specifically, but I'd love to open it up to other devices too, and offer more. Feel free to check it out!
https://github.com/Cian911/tmux-xdrip
This exact symptom literally happened to me a couple of months ago. It was the kinda pain that started in one shoulder and rounded itself up into my head and front temple, and it _always_ started in the early evening.
After doing a bit of research I got myself a monitor, and sure enough my readings one between 150-170/90ish. I'm also a type 1 diabetic to add to it.