Missed diagnosis?

Hi all, I have been bugging my GP for over a year due to diurnal itching. It comes every evening and sometimes during the day also. It was just relentless itching but now it manifests in hives and any irritation to my skin can cause it to worsen.

I finally got him to do some bloods and we found after 3 bloods over 12 weeks that my creatinine is too high and my eGFR is sitting at 72 (25 M). He booked me in for a scan but I have other symptoms too that have been gradually progressing including headaches, brain fog, fatigue and thirst.

I present healthy and fit and I understand T1 typically developes in younger people but is there a way I can test this hypothesis myself to bring to my GP or should I tell him to make me do a fasted bloods. I hadn’t realised diabetes itching is a thing and now with kidney involvement I’m hoping for diabetes over other diseases that mess with kidney because at least i can stabilise that then.

If people had a late diagnosis did you have a similar story? Is the diabetes itch consistent with that I had said? I did notice it worsens when I’m in a caloric surplus or hungover and is better when I try fasting but that’s mostly anecdotal