There are commercial foods that are good to feed for both conditions. You simply need a
low carb, low phosphorus canned food, preferably without byproducts (higher quality protein sources cause less protein metabolism residue, which are easier on the kidneys). Keeping your cat as hydrated as possible is key to managing the disease, along with low phosphorus foods, so definitely no dry food at all (if you're feeding any). Mixing water in with the canned food is one good way to help with hydration. Many people also find that cat drinking fountains also encourage cats to drink more. Anything you can do to get moisture in your cat is important.
The low-protein kidney diets have only been shown to be beneficial in end stage renal failure and should not be fed long term. In fact, they can cause muscle wasting when fed in early stage CKD.
Because diabetes is also a concern, you really need a diet that feeds to BOTH conditions. This is an absolute necessity--there's no point trying to manage the CKD if you're then going to have to deal with uncontrolled diabetes. You have to treat both, or you're still going to have a sick kitty.
Here's an updated food list with the values for several premium foods:
https://docs.google.com/leaf?id=0B8...MzhkYTkxOGM4NThk&sort=name&layout=list&num=50. You're looking for something with less than 10% carbs and less than 250 mg/kcal of phosphorus. The foods I would suggest are Merrick's Before Grain Beef, Merrick's Before Grain Turkey, Merricks' Cowboy Cookout, Merrick's Surf & Turf, Wellness Turkey, EVO 95% Chicken & Turkey, and Blue Wilderness Duck.
If those are out of your price range (although I would strongly urge a food without byproducts, keep in mind that it's still cheaper than the prescription food), the next best thing to feed are the low carb Friskie's Special Diet flavors. These are Turkey & Giblets and Salmon Dinner--make sure they are the ones that say "special diet" on the can, though. PetSmart carries them, and some grocery stores. Here is an updated list of just the phosphorus values for many commercial foods. They can be cross referenced with
Binky's chart for carb values if there's something on there that you want to feed. On this chart, you're looking for something that is less than 1% phosphorus (these values are on a dry matter basis, not mg/kcal):
http://www.felinecrf.org/canned_food_usa.htm
Do NOT use Binky's list for phosphorus values--the carb values are still ok to use but the phosphorus values are really out of date, and some things that were low on that list are now ridiculously high in phosphorus. You can cross reference the carb content from foods on Binky's list with the phosphorus values on Tanya's canned food list, however.
My Gabby had early stage CKD and she was on a med-high protein, low phosphorus diet for the last 2 years of her life. Her CKD did not progress AT ALL on the low phosphorus/high quality protein diet. She passed away from cancer, unrelated to her CKD.
