Well, several members on the forum fast for varying lengths of time and some of them are on various diabetes meds, perhaps they will be along soon to share their experiences. Often as weight decreases the dosage of diabetes meds needs to be altered. Doc will probably advise the eatwell plate -but you can only ask. Good luck either way
Cambridge Weight Plan can usually be followed by a T2 on Metformin;
There are 6 Steps available on Cambridge Weight Plan. A Cambridge Consultant would screen and advise you as a Type 2 diabetic on Metformin, in conjunction with medical advice from Cambridge Medical Section, for the correct Step.
There are too many kinds of diets out there. Just be careful because it is this very people who take advantage of people's problem to enrich themselves. Key is to exercise, eat in moderation and no process or junk food. I know it sounds simple but it is better than spending all that money of those diets.