They have a lot of diseases to keep current on. That is why I always take it upon myself to research myself on top of what my vet says. I have treated 3 diabetics now.
Smokey, my own - vet was pretty current. A few things like not increasing by full units and feeding dry food we found out elsewhere. By the end of her treatment, the vet was completely on board things like 1/4U adjustments. Still liked to try to prescribe too high carb of food, but all in all a very good feline diabetes vet.
Cecil, first foster - vet just about killed him. Put on Vetsulin, then increased the dose based on tests done well past the time when the insulin wore off. He went from an energetic cat to skin-n-bones lying in the corner of the play room or his kennel. I found out the details and talked to the shelter manager. 4 weeks later after a switch of insulin and taking him into foster he was in remission and almost doubled his weight.
Chris, second foster - another vet that treats based on old info and cost of insulin. We tried the insulin for a little while, switched it and haven't consulted with the vet since. Chris will likely start a trial off of insulin in 10-12 days, about 3 months after diagnosis. The vet they have for the other cat that had steroid induced diabetes is even worse. Arrogant and wrong.
Its very disheartening to have vets that treat without first reading up on the disease. I have tried to bring the vets along on my journey with diabetic cats. Them learning along with me is a win for all the diabetics they treat down the line.