I think we need to be more objective with this. When people talk about being "cured" of T2D, I'd like to see some evidence - an OGTT would be ideal.
I could easily say that I'm "cured" with a HbA1c that has never been greater than 5.0% in the last 2.5 years. But I know if I started eating carbs, my BG would go through the ceiling.
It's a good idea. Returning to the Prof Taylor studies / Newcastle Diet, I suspect that the people on that diet would score 'normal' on an OGTT. The reason being that IF Taylor is correct about the etiology, once T2 is reversed by radical caloric restriction the only remaining organic condition is a slight insulin resistance in the muscle tissue. The dominant insulin resistance and impaired beta cell function originating in hepatic fat is gone. He didn't do the OGTT and he might be wrong, but it would be a very interesting test.
If they 'passed' the OGTT you then want to move the goalposts and say "if the cured person ate pie and chips for a year would T2 come back?". Hope you would not!
I think that would be unfair and meaningless. If T2 can be eliminated and kept at bay, it's splitting hairs not to call that cured. The Taylor argument is that T2 has a reversible causation. If you remove the causation it goes away. If you repeat the causation it comes back. Saying that's not a cure would be like saying my broken arm isn't cured because if I put it under a bus, it will break again.