It’s important that you communicate regularly with the school, eg you might want to tell staff if your child’s blood glucose is running lower or higher than usual so they can keep a closer eye on them.
If it’s difficult to speak to your child’s teacher before or after school, you could keep a diary, which the two of you complete and pass to each other (via your child) at the start and end of each school day. In it, you could include blood glucose results or jot down if your child’s had a hypo. It’s just another way of keeping communication channels open.