My fasting blood sugar levels have been all over the place for 5 years. Is this normal?

I was diagnosed with prediabetes in 2020. I've been testing my fasting blood glucose levels on the suggestion of an RN friend (I never followed up with the provider who told me my labs showed prediabetes because I moved, and it was during COVID, so I never saw another provider until I moved again a year later). I haven't been testing very regularly for the last couple years, but I do occasionally. Looking in my log booklet, the numbers are everywhere.

Random 5 consecutive days in 2020: 116, 99, 102, 108.
Random 5 consecutive days in 2022: 87, 98, 98, 98, 90
Random 5 consecutive days in 2023: 97, 87, 123, 86, 96
This year, non-consecutive (I've only self-tested 3 times so far): 91, 112, 76.

Does this even make sense? Is this normal for prediabetics? My PCP thinks I don't have prediabetes because whenever I have had labs done by her, my fasting blood glucose levels were normal, which isn't surprising, because they are normal a lot of the time. But then other days (though very rarely), they're at diabetic levels!