Sorry to hear about your conditions, I only have experience of prediabetes but I see on the NHS site that stress exacerbates symptoms and that exercise and learning relaxation techniques are suggested. Stress is implicated in prediabetes too so tackling this seems a good thing for both. And regular exercise is good for so many things
Apart from it saying low fibre diet and small meals there do not seem to be any blanket dietary recommendations and that you should identify foods that cause problems on an individual basis
So ignore time restricted eating ideas, but exercise good for both and stress reduction likewise. Suggestion is you try and improve your sleep also for prediabetes
I'm sure that you can work out within the foods you can eat without problems and go on from there to address the prediabetes and prevent it tipping over into diabetes. You don't want all the issues this would bring in top of the UC
I did an online prediabetes course during lockdown, which was helpful and I learned a lot. Subsequently I have discovered the Freshwell programme, there is a free app and free online resources, it is a programme devised by a GP practice so there is a lot of science behind it
I hadn't realised before doing the course how carbohydrate in food is turned into sugars which affects your blood sugars, we probably all know to avoid sugary stuff but bread, pastry, etc affects the blood sugars too. And no fruit smoothies- and there was I thinking I was being healthy drinking smoothies and fruit juice. It's almost impossible to go no carb, so I look at the carbs in things, and if there is something a bit carb heavier than usual having protein and maybe some fat to slow down the absorption and sugar spike, with it can be helpful, and doing some walking afterwards, and now I have the blood sugars down I will sometimes have a baked potato with cheese and a bit of butter if I'm out for example. I've found a low carb bread, for times when I fancy a cheese toastie. Apparently if you reheat a potato the starch changes so is a bit better, frozen then toasted bread isn't as bad as bread straight out of the bag. If you cook there are lots of alternative ways of making many things. So I'd start from what you can eat and go from there. Even if you're not prediabetic it is better for your health to avoid sweet starchy foods.
I sometimes miss some of the things I used to eat, and do occasionally have a bit of birthday cake for example or a glass of wine at a wedding, and it is more special than if I ate cake every day so I probably enjoy it more