no, not feeding diseases

I've seen Diabetic -Type 2 - do fruit fasts twice at least - for about 25 days, never having full ketosis, while maintaining normal (no-fasting level normal) BS levels. It was beneficial for him, he gave up all medications after the 2nd fast and was able to eat 2 lbs of sweet cherries on one sitting after the fasts (while this quantity may be not so good to him, though).
Your BS is at normal level, hence it will not feed any disease more than it would do outside of a fasts.