I think that would vary from one gastro doc to another. Some of them may know enough about diabetes to be your diabetes doctor, but I think that would be unusual. An endo is the best specialist for diabetes. If you do not like your current endo, try another. My favorite diabetes doctor is a specialist in unternal ,edicine. He knows just as much about diabetes as most endos. that can also vary though. I am sure there are internal medicine doctors who are not so good with diabetes.