Medtronic Treat to Range (TTR) Closed-Loop Control

1. Clinical diagnosis of type 1 diabetes and using daily insulin therapy for at least one year.
2. Age 15 years to less than 30 years old.
3. HbA1c \< 10%.
4. Subject has used a downloadable insulin pump for at least 3 months.
5. Parent/guardian and subject understand the study protocol and agree to comply with it.
6. Subject comprehends written English.
7. Subject has a home computer with email access.
8. For females, subject not intending to become pregnant during the study.
9. No expectation that subject will be moving out of the area of the clinical center during the study.
10. Informed Consent Form signed by the subject or guardian.
11. Subjects cannot have had a severe hypoglycemic event described as a seizure, loss of consciousness requiring an emergency department visit or hospitalization within 6 months of enrollment.

Exclusion Criteria:

1. Asthma if treated with systemic or inhaled corticosteroids in the last 6 months; Subject has taken oral or injectable corticosteroids within the last 30 days; Current use of oral/inhaled Glucocorticoids
2. Cystic fibrosis
3. Inpatient psychiatric treatment in the past 6 months for either the subject or the subject's primary care giver (i.e., parent or guardian)
4. Use of non-insulin medications that may affect blood glucose (eg Symlin),
5. Systolic blood pressure >140 on screening; Diastolic blood pressure >90 on screening
6. History of seizure or loss of consciousness in the last 6 months.
7. Adhesive allergies; Active skin condition that would affect sensor placement
8. History of heart disease
9. Active Graves disease;
10. Currently on beta blocker medication;
11. Unwilling or unable to follow the protocol;
12. History of diagnosed medical eating disorder;
13. History of known illicit drug abuse or prescription drug abuse;
14. History of current alcohol abuse;
15. History of visual impairment which would not allow subject to participate
16. Currently participating in an investigational study (drug or device);
17. Other major illness that in the judgment of the investigator might interfere with the completion of the protocol: Adequately treated thyroid disease and celiac disease do not exclude subjects from enrollment