What do i do if my friend has a seizure? (diabetes)?

so i have a friend, hes 15 or 16 i don't remember, and hes type two diabetic. he does not take care of himself at all. we always tell him he has to eat right, but he doesn't. his blood sugar level is usually supposed to be around 7-9, but on a regular basis, its anywhere from 24-32. i want to know, what can i do to help him if he has a seizure/goes into a coma when hes with me.