Hi,
Honestly, there is no such distinction as "diabetes vet." There are good vets, not so good vets and great vets. A "great" vet should be able to manage optimum Feline Diabetes care. The best way to find a great vet is call around and ask specific questions about how they treat FD - what insulin (it should be Lantus or Levemir rather than Prozinc, in my opinion), do they encourage home-testing (they should), what diet do they recommend (it should not be a prescription diet), and how many cases of FD have they treated and how successfully.
You have actually found the best feline diabetes care resource, this message board. The collective knowledge and experience here outweighs that of probably 99% of vets where feline diabetes is concerned. Yes you need a vet to support what we know works for most of cats, so that's why you should call around to find one which supports our recommendations for the basics (diet, insulin, & home-testing). Even great vets may not be familiar or even agree with the those FD basics, we always have someone come on board saying how much they love their vet and have gone to them for years, but the treatment they have outlined for FD is not to our standard because of the diet or insulin choice, etc.
Hope that helps.