Hi mate,
Firstly to bassboy.
That has to be one of the best and most helpful replies i've seen for ages.

I was going to reply as i have an Uncle who is diabetic, and I work with a lad who is too, and occasionally they have a hypo, and we need to get a sugary drink into them as quickly as we can. But there is nothing I can add to what bassboy has written.
I would just like to say that whilst it can be serious, it can be handled with a little care and medication, so there is no worry on that score.

I hope all goes well for your Dad and you mate.