What is pre diabetes

Pre diabetes is glucose intolerance, or insulin resistance, which means that you may develop T2 diabetes in the future if you don't make changes to your diet, exercise regime, etc.

http://en.wikipedia.org/wiki/Impaired_glucose_tolerance

Theoretically the cutoff point is set where the disease process becomes irreversible

http://www.bloodsugar101.com/

however the sooner you start to get to work on the problem the more likely you are to avoid progression, the argument is a bit like how many angels can dance on the head of a pin: if your BG is going outside of normal parameters it makes little difference what you call it.