Hi,
I am not going to be much help I am afraid, as I don't know teh answer to your question. I guess, as I diabetic yourself, like your Mum with you, you are the best person to recognise teh signs...but this doesn't really help I know! I confess, that if either of my children has quite a bit to drink, I watch them a hawk...if they go to the loo more than once an hour of so, I am twitching to test their blood!! I have only done it once (they are 4 and 2) but it is a paranoia of mine. Will one, or both of them get it? I don't know, I hope not, but as there is nothing I can do to stop it, I just have to live with teh worry. I guess as T1s ourselve we are in a great place to cope, should our children be diagnosed...and as we know, whilst I would not wish this condition on anyone, ithas not stopped me having a great life, and doing what I wanto to do with it, so I am not going to let my worry about it impact their lives at all.
As to age, urrmm, I don't know. As I was 4 at diagnosis, the fact that my daughter is nearly 5 and diabetes free is giving me hope...although I have nothing to base this on.