Hi & welcome Elijahfan
Best wait for diagnosis and recommended treatment, before speculating too much about possible effects. But, likelihood is that a child of 7 years will need insulin, which has to be injected. However, there are several ways of administering it, each with plus and minus points - basically, twice daily injections, which need meals with set amounts of carbohydrate at fixed times OR multiple daily injections, usually 1 long acting, plues 1 short acting with each meal (or large snack) OR pump: a canula inserted into skin, where it stays for several days, connected to small battery powered pump. In all cases, finger prick tests are needed, and can give more freedom to adjuts doses according to what child wants to eat (mainly need to adjust for carbohydrate content), do (particularly physical activity, not just sport, but also walking, cycling, dancing, acting), plus also to compensate for infections, air temperature etc. Many parents aim to adjust insulin to child's diet, rather than adjusting diet to diabetes, but it does depend a bit on what diet is like before diagnosis.
Anyway, there's lots of advice available here, from parents, teachers and adults who were children with diabetes quite recently, so just ask away.