I think advanced insulin resistance would be a better name and identify there are many warning signs and issues before most people develop full blown type 2 diabetes
The diet they used in the study was a low carbohydrate, less than 20% of intake is carbohydrates, which is about 85 g of carbohydrates per day.
Of course the population here was quite motivated to adhere to the program, being diabetic and wanting better outcomes. There was no control other than food survey's here.