Based on experience of three people I know who are diabetic and talk about it and my work place first aid training.
There is no answer that will fit all diabetics as all are different in the way diabeties affect them and the way they manage it.
The management varies from hour to hour depending on activity levels and previous food intake.
The majority of adult diabetics can self manage and will decide what they can and cannot or must eat at the time.
Many children can self manage but may need supervision when involved in physical activities as they may not be aware of an impending hypo ( low sugar ) until it is too late for them to act for themselves.
Young children cannot self manage and do need to be monitored and managed. You will have to talk to parents and ( with parent's permission ) maybe the child's doctors as to what care will be need to prevent the child having an episode ( hypo or hyper ) and what treament you can give if an episode does happen while the child is in your care.