As I keep posting on here thin people are just as likely to have visceral fat as overweight people and the Newcastle Study was to study the effects of reducing/removing visceral fat by using a very low calorie diet over a short period.
You cant see visceral fat but it is this fat which causes insulin resistance and if it is reduced then the insulin resistance is reduced which causes high bg levels, again not a cure as if the visceral fat comes back so will the insulin resistance and thus the T2 diabetes. If you are a thin person who has visceral fat you will always be predisposed to it unless you change your diet/lifestyle.
The best thing any T2 diabetic can do to help themselves is lose their visceral fat as the Guardian article testifies. But if it is a particular diet that causes visceral fat in the first place then it is likely to return unless the diet is changed to healthier choices. Maybe its processed foods that cause visceral fat to be laid down, maybe it isnt, maybe its saturated fats and maybe it isnt.
As with all these things more research needs to be done to identify the causes of visceral fat, the only thing we know for sure is it is not good for us.