Hello. First, as a parent to ONE T1 toddler, age 2, I can’t imagine two and my thoughts are definitely with you. I don’t have any direct, first hand, knowledge into what this could be but I did find a similar post about this same thing from 2008 – perhaps it can shed some enlightenment on the matter!
High blood glucose in non diabetic child
I hope things work out! Stay strong and positive.