If a person's blood sugar is really high and they go into a coma. doctors would try to bring the blood sugar down, correct?

Yes. Slowly. : Yes but it needs to be done slowly and carefully to prevent brain swelling. It is not all about the blood sugar or glucose. The sodium and other electrolytes are very important. It's a very delicate process that must be carefully monitored. And each patient is different. Adults are treated different than children and children must be even more carefully corrected.