If the child was tested just after arriving at school, I'm guessing that insulin was still on board to cover the carbohydrates consumed. It would not be unexpected for blood sugars to be elevated with no ketones. It's happened with my child. I would hate for the school nurse/TDMP at his school to feel like I was not being truthful; or worse, negligent. People who don't have a child with diabetes really have no idea how difficult it is to manage this disease no matter how many credentials are listed after his or her name. My gut reaction to this OP was that I felt completely insulted that someone caring for my child could question my ability to care for my child based on one high blood sugar reading. This is exactly why Connor's health care plan does not allow school to test ketones. I would immediately come get him and test ketones myself if my son threw up at school. Also, I am notified by phone of any numbers over 350 and I can decide a course of action depending on the situation. Sometimes I come get him if he's symptomatic/ie feeling ill. Sometimes it just to follow the sliding scale and push water. It's so important to have open communication between school staff and the parents.