Type 1 diabetes mellitus (DM) affects about 1 in 500 children and can cause damage to multiple organ systems. In recent years, growing attention has been given to the effects of type 1 DM on the brain. In this article we review important imaging features of the brain in children with type 1 DM, including (1) imaging the child in diabetic ketoacidosis and the child with hypoglycemia, (2) syndromes associated with type 1 DM, and (3) long-term effects of type 1 DM on brain structure.