Hi..Some Non Diabetic people have numbers very high after eating certain things..it depends on how long it takes for them to return to normal. I am not familiar with how children's numbers run. To actually determine if he is a true Diabetic they should run an A1c and also a glucose test. I believe the glucose test measures fasting..one hr. and then 2 hrs.
I've seen people on here go for the glucose test and although their numbers were high they returned to normal within a certain time frame and were told they were NOT Diabetic.
Hopefully someone with more knowledge then myself will beable to answer your questions.
Wish you the best and please keep us posted..JJ...