Stop eating sugar.
This has been posted before.It can’t be cured, only managed. Some can lower their A1C (I went from 13.5 to 6.0) and it can mean taking less or no insulin and modifying metformin, etc. In my case I went from 30 units daily to 24 and now 18 though I’ll have to take 4 metformin pills (total of 200 mg) daily. This through diet, exercise, medicine.
Well, actually ANY simple carbs which end up as sugar.