I often think that as it's an autoimmune disease then doesn't it mean your immune system is better than others? Before my son was diagnosed I would say that he was NEVER ill. Even nasty colds that others had he seemed to have over and done with in a day or two.
Interestingly though, in his first year post-diagnosis, he had no less than 8 colds 😱 I was quite shocked by that and remember asking the same question on here.
I have to say of myself though (non-D) I have one bad winter where I catch cold after cold, then I seem to go years with only one at most - I'm sure it's just the immune system having time off occasionally and letting you catch everything, to re-stock the antibodies. I have remained cold free so far this year despite working with children, all bringing their germs in, but I have been struck down with the dreaded novovirus, yet my lad didn't catch that off me.