Roughly 5% and 20%
If a male has T1DM then there is a 5% chance a child will develop it.
If a primary relative has Celiac there is a 20% chance.
These are population based and many other factors are at work, most unknown / unproven. While high on the population level the main thing to note is that it is MUCH MORE LIKELY that your child WILL NOT develop either. I would not recommend special precautions or testing.