See what your vet recommends, ask if Nutrisca would be a good option?
“Nutrisca is one of the only grain free recipes without potato or tapioca, which are high on the glycemic index and contribute to weight gain. Instead, low glycemic chickpeas and peas are included as excellent sources of protein, fiber and folic acid”. https://www.chewy.com/nutrisca-grain-free-turkey-chickpea/dp/36099
VeRus has some excellent canned food choices. They are all BPA & BPS free. While they don’t specifically mention a diabetic formula, all flavors will work well with a diabetic dog. If you have questions, just contact them via the contact form. They’ll answer quickly & help you out.