I’m not up to date on diabetes management but I think that type 2 is is still thought to be caused by insulin resistance - your pancreas has to produce more and more insulin to control blood sugar levels and eventually can’t keep up. There is a pre-clinical stage where your pancreas is working harder but still keeping sugar levels normal.
There is evidence that cutting down calories, loosing weight and possibly taking metformin helps prevent or delay the onset of type 2 (I recall that there was quite a landmark study on this but will have to look for the details).
It makes sense that if you adjust your diet, cut down calories, cut out as much refined sugar as possible then you may well get back to the point that your pancreas can cope - I suppose this could even slightly reverse the underlying metabolic problem but I’m not sure how much evidence of this exists.
After all initial management of T2 is often dietary - and some people can do really well if motivated, look at Tom Watson.
Of course, watching what you eat, cutting down the weigh and getting a bit more exercise, seem sensible goals for most of us.