"Eight weeks using the diet helped those who took part to lose weight and reduced the amount of fat in their liver and pancreas. Doing so helped to restore their insulin production and put their Type 2 diabetes into remission. Three months later, some had put weight back on, but most still had normal blood glucose control." (from Diabetes UK website)
Michael Mosely suggests maintaining the weight loss afterwards using 5:2 (but at the 800 cal level rather than 500/600). It peaked my interest because, although I am not diabetic or pre-diabetic, all my fat is abdominal so I'm a prime candidate for it in the future (plus it is in my family). Worth a peak.