I think, so far, the only evidence we have suggests that 'reversal' (reverting to normal glucose tolerance) is possible
- in the short term
- for a minority
- as a result of weight loss to below their 'personal fat threshold'
We have no idea what will happen to the individuals who 'reverse' in the longer term (5 or 10 years), and they must retain their weight loss below their 'personal fat threshold', which may vary over time.
There is no evidence (that I have seen) suggesting that any one method of weight loss (e.g. vegan, or 'wholefoods', or diet shakes, or Mediterranean, or LCHF) is more effective in achieving 'reversal'. The key factor seems to be visceral weight loss, and no diet is able to target that specifically.
Edited to add the last sentence.