It might be an option to find a specialist that will/can work with the local vet. I feel your pain. I have several vets very close but drive 35 min away for Gizmo's. The quality of care, the modern facilities and the competent (caring) vets are worth it.
Make a list of tests you need done. List of questions. Basically be prepared and organized. Don't let them bully you. Ask if they gave ever treated a high dose kitty and if so, what their success rate is (my vet is that they have not treated one, most have not). Find out what lab the send the bloodwork to (IDEXX or ?, can't remember the other large lab). If they don't use either, ask if they would/could. Take all lab reports that haven't been done by the new vet.
Do you have a tablet? If so, take it so you can show the spreadsheet, testing and dosing. Make a list of the foods you are feeding. Take a print out of the low carb food list. Basically show them you know what you are talking about and you need them to work
with you for the best of Gizmo.
There used to be a "vet interview" page but it no longer exists

. Maybe someone still has a copy?
what to look for when interviewing a vet