I found this on a website......
Dr. Lisa Pierson has written extensively on the topic of Feline Nutrition (and Common Sense). I highly recommend her website
http://www.catinfo.org/ for information about Feline Diabetes, and she also has instructions for making cat food, complete with a recipe.
If making your own cat food is too much work, Dr. Pierson also shows you how to read the ingredients (especially carbohydrate levels) in the commercial brand and prescription canned foods.
Make sure you discuss your kitty's diet plan with your veterinarian, because the insulin levels may change and will need to be monitored closely.