Yale-Harvard Hotel-based Closed-Loop Studies in Children (HY-GRAID)

Inclusion Criteria: 1. Age 2- \<18 years; for first cohort(s), subjects will be 12-17 years; additional age brackets will be 8-11 years and then \<8 years 2. Type 1 diabetes for ≥ 1 year duration - the diagnosis of type 1 diabetes will be based on the history of ketosis/ketoacidosis at diagnosis or laboratory evidence of islet-cell auto-immunity 3. A1c level ≤ 10.0% 4. Use of insulin pump and carbohydrate counting for ≥ 3 months 5. Average total daily insulin dose of at least 10 units/day 6. Current or past use of Continuous Glucose Monitoring (CGM) is desirable but NOT required 7. Normal renal function as measured within 6 months of enrollment 8. Normal thyroid function within 6 months of enrollment, or if previously diagnosed with hypothyroidism, documented within 3 months of enrollment 9. Parent/guardian agrees to stay at hotel with subject for duration of hotel phase and has cell phone that can send/receive text messages 10. Subject and participating parent/guardian speak and comprehend English Exclusion Criteria: 1. Episode of diabetic ketoacidosis (DKA) within 6 months of enrollment 2. Episode of severe hypoglycemia (seizure, loss of consciousness) within 6 months of enrollment 3. Use of medications (other than insulin) known to affect BG levels within 4 weeks of enrollment - examples include systemic glucocorticoids, metformin, pramlintide, liraglutide) 4. Current use of other medications, that in opinion of investigator, would interfere with safety or effectiveness of the study including acetaminophen 5. Medical disorder, that in opinion of investigator, would be contraindication for inclusion; hypothyroidism and celiac disease are NOT exclusion if under good control 6. Female subjects of childbearing potential unwilling to have pregnancy testing 7. Female subject currently pregnant or lactating 8. History of alcohol or drug abuse, documented eating disorder, or inpatient psychiatric treatment within 6 months of enrollment 9. Subject is currently participating in another research study involving an investigational drug or device