My daughter's breath used to smell sweet every time she was ill, from when she was a baby onwards. I found this slightly alarming at first, but the smell always used to go away again once she got better so I eventually decided it must be something to do with starvation ketones due to her going off her food when she was ill. The problem came when she got a nasty virus on the night of her 6th birthday, one of those horrible ones which knocks you out for a week and then it takes another week for you to get fully back to normal. As usual my daughter's breath smelt sweet, but that time the smell didn't go away again after she got better... 7 weeks later she was diagnosed with T1

I very much doubt that any of the sweet smell when she was a baby was anything to do with T1, but am pretty sure that the nasty virus when she was 6 is what triggered her diabetes.
I have no idea what Viakal smells like, but presume this is the sort of thing you are talking about
🙂