I think that Dr Fung's success is counted in the number of his patients who have been successful who probably number significantly more than the ND trials which have involved so far 40 people.
There are a lot more people who have done the ND, the Newcastle team knows 100s but don't have data on them that is good enough to publish. About 50% of the people who have claimed to have done it themselfs, claim to have reversed their diabetes. Then there will be 1000s of people who have acted on the "blood suger diat" book in some way.
I find intermitant fasting and low carbs is the best for me, as I do all the cooking and my wife would rebell if I make her do the ND! But ND clearly works for lots of people. I expect that anyting other then the standard NHS "moderate" low fat diet gets good results....
Lets also remember that most people who have "failed" to reverce their diabetes are still in much better health then if they had done nothing.