Medtronic Minimed Overnight Closed-Loop System

Inclusion Criteria: To be eligible for the study, a subject must meet the following criteria: * Clinical diagnosis of type 1 diabetes and using daily insulin therapy for at least one year and a Medtronic insulin infusion pump for at least 3 months The diagnosis of type 1 diabetes is based on the investigator's judgment; C peptide level and antibody determinations are not required. * Age 10.0 - 35 years Exclusion Criteria: The presence of any of the following is an exclusion for the study: * Diabetic ketoacidosis in the past month * Hypoglycemic seizure or loss of consciousness in the past 3 months * History of seizure disorder (except for hypoglycemic seizure) * History of any heart disease including coronary artery disease, heart failure, or arrhythmias * Cystic fibrosis * Current use of oral/inhaled glucocorticoids, beta-blockers or other medications, which in the judgment of the investigator would be a contraindication to participation in the study. * History of ongoing renal disease (other than microalbuminuria). * Medical or psychiatric condition that in the judgment of the investigator might interfere with the completion of the protocol such as: * Inpatient psychiatric treatment in the past 6 months * Uncontrolled adrenal disorder * Abuse of alcohol * Pregnancy