Additional Study Information: We are conducting a study to understand the brains of people with type I diabetes mellitus. We are recruiting both people WITH and WITHOUT type I diabetes between the ages of 13 to 35 to participate in this study at Columbia University Irving Medical Center/New York State Psychiatric Institute. Participation involves: One in-person interview to determine your eligibility (up to 1-2 hours), urine test for substance use, and magnetic resonance imaging (MRI) scan of the brain (up to 30 minutes). As a participant you will receive: Up to $130 over two visits, as well as reimbursement for local transportation. If you are eligible, you can also receive additional reimbursement as a standby subject (meaning you'd come in on a day when someone else is scheduled in case they don't show up).