Unfortunately, there have been few FDA approved insulins available for dogs and cats over the years. Eating patterns can affect which insulin is best for a pet.
Cats tend to be nibblers (eat a bit all day long), so longer acting insulins such as PZI and insulin glargine (Lantus) are popular choices by veterinarians for diabetic feline patients. Longer acting insulins do very well with the low-carb/high-protein diets for our cat patients. The “diabetic” feline diets are low-carb/high-protein and cause little spike in blood glucose. Think of the Atkin’s Diet for humans: It is a low-carb /high-protein diet. Kitties are true carnivores and do well with low carb diets. Low-carb/high-protein diets are much like what a feline would eat in the wild.
Canned food has much lower carbohydrates than dry food. The feline diabetic dry foods have lower carbs than other dry foods, but they still are higher in carbs than canned food in general, particularly canned kitten food. If your cat is finicky and refuses canned food, hopefully the diabetic dry foods will tickle her fancy. Nonetheless, most veterinarians today recommend canned food only to their diabetic feline patients. The initial studies done with low-carb diets for feline diabetes were done with canned kitten food.
Cats in America tend to be type 2 diabetics initially, oftentimes from obesity. As type 2 disease progresses the pancreas can become exhausted and type 2 diabetics may turn into type 1 diabetics. Type 2 diabetic cats can potentially regress to a non-diabetic state if treated appropriately early on, so when your veterinarian tells you to use a low-carb diet for your kitty, please listen! They say about a third of type 2 diabetic cats can become non-diabetic with long-acting insulins, weight reduction for obese cats, and low-carb diets. I have personally had at least 1/3 of my feline patients revert to a non-diabetic state with this approach.
Always keep in mind that exercise, maintaining a healthy normal body weight and proper diet will ultimately improve glycemic control.
I hope you find these general suggestions worth your while.
NOTE: Consult your veterinarian to confirm that my recommendations are applicable for the health needs of your pet.