Without going into a lot of detail at this point, my doctor tells me that I am pre diabetic.
He says that if I don't do anything about this, I will have full-blown diabetes in 6 months to a year. No doubt. Is this typically the case?

If so, what would cause me to be considered pre diabeteic for over 17 years, but not diabetic? No family history of diabetes either.
I just want to find answers. Seems like there is something more going on here, but my doctor won't even consider that there might be something else here.

Thanks.