Without knowing treatments that have been done over the course of the month this has been going on, recommendations here are basically shot gun - hit or miss.
What kind of diagnostics have been done? If she is a toy poodle and on 10 units twice a day (what's her weight?) how good is her glucose control? I'd also be wondering about Cushings disease.
Things you can start to do at home are the probiotics (raindove recommended the yogurt).
With a diabetic, I'd be wondering if the pancreatic exocrine function has stopped as well as insulin production. Perhaps the solution would be to try supplementing digestive enzymes (viokase, pancreazyme), suggest this to your vet if it hasn't been done.
Switching diets repeatedly may create more problems and hinder diagnosis.
PM me if you need to discuss details of a diagnostic or therapeutic plan.
Doug, DVM