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.
Here's the Amazon link for book about the program and you can also read the reviews of many people who have successfully changed their for the better as well: http://www.amazon.com/Neal-Barnards-Program-Reversing-Diabet...