Anecdotally, my father didn't develop the disease until after he went on a ketogenic diet, but the doctors believe chronic lack of sleep caused his diabetes so diet probably was not a factor either way.
That's unfortunate. Type 1 or 2 diabetes? My mother is T1 and she cannot do a low-carb diet because of the possibility of ketoacidosis, which she's already been hospitalized once for.
I would suggest she tries the program created by Dr. Neil Barnard in this case as he actually uses a low fat high carb diet in order to reverse diabetes. Both my father and father-in-law got rid of the medications (my inlaw even had to take insulin before the program) and have overall improved their health, lost weight and are feeling much more energetic. My father was able to be out of his medications after two months and my father-in-law in 4 months.