Maybe this will help.
Diets For Diabetic Pets
These diets rely on higher protein and lower carbohydrate to help stabilize blood glucose since the protein in food is converted to glucose slower than the starch. The results of increasing or decreasing fiber content in the diet of diabetic cats are not consistent. What is probably more important is that your cat stay at a normal body weight and consume its diet slowly throughout the day. Dogs seem to do better when their fiber intake is increased.
A well-established routine that combines regularly scheduled meal times, treats, and exercise is very important in maintaining your diabetic pet's good health. Reducing your pet's weight to an optimal level is also very important. You do not want your diabetic pet to be too fat or too thin.
You will need to experiment with various recipes and feeding times and see what works best to control your pet's blood sugar level. The best way to monitor your pet's blood sugar is using a glucometer at home to monitor its blood sugar level. In cats, you may get by using Glucotests.
In people, dietary changes alone often make insulin therapy unnecessary. This can occur in pets as well.
Commercially formulated diets for diabetic pets have increased omega-3 and omega-6 fatty acid levels supplied by fish oils and flax seed and increased levels of vitamin E . Sunflower and canola oils are good sources of natural vitamin E.
And this:
Homemade Dog Food for Diabetes Control | eHow.com