Hi EHorst99 & welcome to this forum.
I do think that a 3 -5 hr glucose tolerance test is a great idea, i was around your age when my symptoms first started and was overweight & inactive as well, Prediabetes can certainly cause the exact same neurological symptoms as a full blown diabetic, any neuro that disagrees with that, is not up to date with current neuro findings.
Things can get better, especially if the cause can be found and rectified, other idiopathic PN 'ers have improved with supplements, [ read the stickies on the front page up top ] peripheral nerves do have the ability to regenerate once in the right enviroment.

best of luck to you, i hope you can find the cause.

Brian