We have a black lab who has diabetes for over 5 years. She gets 23 units of insulin twice a day, and eats a controlled diet, and a supplement for diabetes. The supplement makes a HUGE difference than just the insulin. We started with just the insulin and diabetic dog food, and latyer added the supplement. The, my mom wasnt sure if the supplement was actually working (dog had been on it a few years) so took her off it for a few weeks. Well, it was then apperant how much it helped when she was on it. If your interested IO can ask my mom the name of the supplement. We actually found that the diabetic friendly dog food you get through the vet doesn't work for her. Even on it and insulin her sugar wouldn't come down. We tried a lot of different foods to find what worked for her, and it ended up being Nutro natural choice senior. Not the highest quality dog food, but I would consider it a good mid grade, and it works for her. Do you have the machine to check her sugar at home? If so Is her sugar spiking at certain times, then bottoming out, or does it stay constant? What brand of insulin does she get, we have had better luck with some then others.
I'm glad to hear your vet caught it early. Our OLD vet kept saying that it was the dog getting old, allergies (she had diabetic ulcers and looked almost like mange around bald spots) and so forth. My mom kept telling him something wasnt right, but he blew her off. One day she walked face first ionto a wall and we took her to the vet and demanded they check her sugar, and it was way high. She went blind that day, which is why she ran into the wall. We now use a much better vet who listens and takes what we say into consideration.