Hi
My son is 16 and was diagnosed with T1 at age 11. He regularly and freely drinks the Robinson's No Added Sugar drinks. Although there is a little sugar in it, its not sufficient to be an issue. The same with childrens' meds - if there isn't a sugar-free version, I would go ahead and give a regular one on the basis that a 5g teaspoon of sugary syrup really isn't going to be a big deal.
When my lad was first diagnosed, I spent ages in supermarkets - reading labels and being very conscious of choosing diabetes-friendly items. Now, I just buy as normal and we adjust his insulin to suit what he is consuming, by carb-counting.
I like to repeat a saying which is popular with parents of children with T1 and that is ....."There are only 2 things he/she cannot have 1) Poison and 2) Any food or drink that has poison in it".
Just be careful when buying fizzy drinks from 'the tap' in food and drink outlets. You may not always be served with the diet version when you order it. Best to buy in cans/bottles whenever possible. I have heard it said you can test your soft drink using either your BG meter or urine sticks if you really want to check!
Best wishes.