Hi OP, I have gone from one 'point' away from full blown diabetes (so well into the pre-diabetes range!) to normal. The time between tests was 12 months and I think the key here is time and not rushing, these will need to be forever changes so don't rush and make gradual changes.
I found the Zoe app very helpful, I did fork out for the works which seemed very helpful at the time but now my diet is permanently changed (4 years on) I don't know if all the initial faff was that worth it. I changed one single thing every week, that was all. I swapped out fizzy water for diet drinks, upped my fruit and vegetables, added pulses as much as I can to everything (handful of lentils can hide in nearly everything if you are careful). Hardest thing now is everything is cooked from scratch but if I eat jar sauces or over processed food I really don't like it anymore so, cooking it is.
That's it really, it's a Mediterranean diet basically, lots of olive oil, garlic and avocados, no processed foods, a lot less sugar and huge amounts of fibre. My fridge is never without 5% fat greek yogurt by the literal barrel and I use soaked cashews to blitz in my curries instead of cream.
Can't think of anything else off the top of my head, feel free to ask me questions if you have any. I've lost weight (started exercise as well) but more importantly to me my blood pressure is good, cholesterol going down and no longer pre-diabetic. Much healthier!