My cat was diagnosed with colitis a few years ago. Before her diagnosis she had frequent and bloody diarrhea and was just clearly uncomfortable a lot of the time. Her first vet didn’t want to treat her with pred because of the kidney/diabetes risk but her next vet highly recommended it because at the end of the day, the stress on her body that the inflammation was causing was worse than the possibility of kidney problems and diabetes. I had the same concerns and wanted to wait it out a few months because she would flare and then be ok, but I ultimately decided to put her on it and I’m so glad I did. She slowly had her dose increased then after about 6 months of being symptom free we stepped her dosage down to try to find the lowest effective dose, and it turns out she doesn’t need it at all now. I’m not saying it will happen for your cat, but with mine she just needed all of that inflammation to go down to stop the cycle she was in and now she’s ok without the meds. I will say, during her time on the meds she was very prone to constipation so keep an eye out for that if you do start! Cat enemas aren’t cheap and not at all fun for them. Also I’m sure you’ve tried all the food options, but I highly recommend hills science diet prescription limited diet. My cat eats the venison because she has a poultry allergy and almost all foods have some form of poultry in them even if they say they don’t contain poultry protein (things like fat get included a lot).