@suzanjg my dog initially was on vetsulin and did very well (https://www.vetsulin.com/dogs/vetsulin.aspx) it is available again now I think. Around 2009 they stopped producing it so we had to switch to Humulin, which is the same as Novolin I believe. The vet should have done an initial test to set his dosage? They then calculate how much insulin he needs, however even small changes in excercise and diet will change that. Only home testing will tell you if his sugar is correct. A simpler and less accurate way is to test with Diastix which will let you know if he is too high, test him twice a day and if they change color, then take him back to the vet. Vets are not diabetes specialists and it is a complicated disease. The Diastix will only tell you if his sugar is way too high, I presume the vet told you to load up syringes of syrup in case of him going low? My dog only went low once at night in the whole six years but it is an emergency if they do. The key is to stick to a routine that works and don’t change anything, weigh his food so there is consistency, excercise consistently, check his sugar regularly. No regular dog treats as most will spike his sugar, fresh unprocessed chicken is ok in moderation etc.
I had a dog diagnosed with diabetes when he was five, managed it for six years and he passed of cancer when he was eleven. Not much I don’t know about it and each dog is different, mine was a very fickle diabetic and I had to test him several times a day with a special dog diabetic meter called an AlphaTrak. What insulin are you using? They used to have a good one specially for dogs but they discontinued it when mine was diabetic. It’s a tough disease to manage in a dog but you can do it. You have to balance food, excercise and insulin carefully.
I think with time, good training and trust, anything can be overcome. Having said that, they all share traits but have their own personality. My first was very self assured, assertive and defensive, but never aggressive. He would growl but not bite. My second is food aggressive, always has been. She would bite first with no warning at one point if you went near her food. With time she has mellowed a lot and is now twelve, I can take food off her. My third doesn’t have a mean bone in his body. Growling is a natural warning, so although it should be minimal, it is normal.
Another thing I always put on is “REWARD”, some engraved tags have both front and back engraving. I also bought a really nice leather branded one with my dogs name and phone number worked into it, really awesome quality off an eBay seller, there are lots, here is one listing. https://www.ebay.com/itm/Custom-Saddle-Tan-Leather-Dog-Collar-Your-Dogs-Name-1-wide-Hand-Tooled-G-E/381520270584?hash=item58d46154f8:g:R4YAAOSwux5YP46M
Grooming is normal. However excessive licking is likely because their stomach is off. When my Bandit feels sick, he licks excessively. Two things help, first three or four smaller meals throughout the day help stop the yellow bile. Secondly not overfeeding helps, if he overeats he will be sick. I am sure a good quality possibly grain free diet helps some dogs too, as mine sometimes has allergies.