They have been reversing type 2 diabetes in studies at the University of Newcastle, UK for some time.

"A body of research putting people with Type 2 diabetes on a low calorie diet has confirmed the underlying causes of the condition and established that it is reversible."

The underlying cause is fat within the liver and pancreas. They have been reversing the diabetes by putting patients on a very calorie restricted diet.

http://www.ncl.ac.uk/press/articles/archive/2017/09/type2diabetesisreversible/