Sorry smurfchops, I'm sure you're really upset and worried. My cat was diagnosed with this in October last year. I was not given the option of diet so can't help on that. Common sense would tell me that it would have to be only mildly above normal for a diet alone to control but I'm just guessing. My cat was old (17) so they wouldn't give me the option of removal as it would be too stressful so I ended up with the tablets. It did become a right pain getting those down her every day. Had she been younger I'd have definitely opted for removal.
Only vets can advise really though.