I second the vote for something grain-free with a good moisture content (canned or raw). Moisture should help with the UTI issues, and grain-free (and low-carb in general) is the best idea for a cat with diabetes. Grains are processed into sugars by the body, which provides a source of energy, but in cats, it isn't the preferable choice because their bodies sometimes just cannot handle that kind of sugar load, thus grain-free is a good idea for a cat with diabetes (and even for those without, to help prevent diabetes). They're better off getting their energy from the proteins and fats found in meat.
All the canned brands mentioned above are excellent ones (I think there's another member here who has a kitty with IBD who feeds Natural Balance LI and has spoken highly of that). I've fed my cats Evo, Merrick Before Grain, Blue Wilderness, and Wellness at varying points in time and have been very happy with them all.
I don't know if my Athena has IBD as I've never had her tested, but she has an extremely sensitive stomach (soft stools, bloating, and gas in response to the wrong foods) and so far grain-free canned and raw are the only things that have helped her, with raw showing the best results. Any kind of kibble (including just a single meal of a quality grain-free kibble) or any food containing grain produce the worst reactions in her, so I'd recommend avoiding those with a sensitive-stomach kitty.
I currently have my cats on a regular schedule of Primal raw with some occasional grain-free canned (rotating the above mentioned brands) and Athena's been doing very well on this diet. No more digestive issues at all.
Last edited by saitenyo; 04-22-2011 at 01:04 PM.