I'm the same, I have a holiday planned in 3 weeks but a few months ago a day out ended with DKA due to an u known bladder infection and 24hrs in hospital. I agree with above, make sure he has all the kit he needs, ketone strips for urine and blood strips which are more accurate and a thermometer to check for signs of infections. Phone your diabetes nurse and go through sick day rules. Knowing what to do if you are unwell and having the kit to tear yourself will help. My GP has given me broad spectrum antibiotics to take with me and start taking of I get infection symptoms such as high temp and ketones. Also knowing your loved ones know what to do helps too.