Omnipod Horizon™ Automated Glucose Control System Preschool Cohort

Subjects will undergo a 14-day outpatient, standard therapy phase during which sensor and insulin data will be collected. This will be followed by a 94-day (13-week) hybrid closed-loop phase conducted in an outpatient setting, and an optional 12-month extension phase.

The study schedule will consist of a standard therapy data collection phase followed by a hybrid closed-loop phase.

Subjects will undergo a 14-day outpatient, standard therapy phase during which sensor and insulin data will be collected. Subjects, or their caregivers, will manage their diabetes at home per their usual routine using the study continuous glucose monitoring system (CGM) and remain on current multiple daily injections (MDI) or pump therapy. This will be followed by a 94-day (13-week) hybrid closed-loop phase, conducted in an outpatient setting where subjects, or their caregivers, will manage their diabetes at home using the Omnipod Horizon™ Automated Glucose Control System. After completing the 94-day hybrid closed-loop phase, subjects will have the option to continue using the system for an additional 12 months.

During the hybrid closed-loop phase, a subset of subjects will participate in 2-days of supervised meal and exercise challenges.

The hybrid closed-loop phase will begin on Study Day 1.

Eligibility Criteria:
Inclusion Criteria:

1. Age at time of consent 2.0-5.9 years
2. Living with parent/legal guardian
3. Diagnosed with type 1 diabetes. Diagnosis is based on investigator's clinical judgment
4. Deemed appropriate for pump therapy per investigator's assessment taking into account previous history of severe hypoglycemic and hyperglycemic events, and other comorbidities
5. Investigator has confidence that the subject and/or parent/guardian/caregiver can successfully operate all study devices and is capable of adhering to the protocol
6. Willing to use only the following types of insulin during the study: Humalog, Novolog, Admelog or Apidra during the study
7. Willing to wear the system continuously throughout the study
8. Willing to participate in challenges for 2 consecutive days, consisting of a minimum of 3 hours of activity per day and dietary challenge by reducing the number of carbohydrates entered for a given meal by 50%
9. A1C \<10% at screening visit
10. Subject and/or parent/guardian must be willing to use the Dexcom App on the Omnipod Horizon™ PDM as the sole source of Dexcom data (with the exception of the Dexcom Follow App) during the hybrid closed-loop phase
11. Subject and/or parent/guardian is able to read and speak English fluently
12. Has a parent/legal guardian willing and able to sign the ICF.

Exclusion Criteria:

1. A medical condition, which in the opinion of the investigator, would put the subject at an unacceptable safety risk
2. History of severe hypoglycemia in the past 6 months
3. History of DKA in the past 6 months, unrelated to an intercurrent illness, infusion set failure or initial diagnosis
4. Diagnosed with sickle cell disease
5. Diagnosed with hemophilia or any other bleeding disorders
6. Plans to receive blood transfusion over the course of the study
7. Clinical evidence of acute or chronic kidney disease (e.g. estimated GFR \< 45) or currently on hemodialysis
8. History of adrenal insufficiency
9. Has taken oral or injectable steroids within the past 8-weeks or plans to take oral or injectable steroids during the course of the study
10. Unable to tolerate adhesive tape or has any unresolved skin condition in the area of sensor or pump placement
11. Plans to use insulin other than U-100 insulin intended for use in the study device during the course of the study
12. Use of non-insulin anti-diabetic medication other than metformin (e.g. GLP1 agonist, SGLT2 inhibitor, DPP-4 inhibitor, pramlintide)
13. Thyroid Stimulating Hormone (TSH) is outside of normal range with clinical signs of hypothyroidism or hyperthyroidism
14. Currently participating or plans to participate in another clinical study using an investigational drug or device other than the Omnipod Horizon™ Automated Glucose Control System during this study period
15. Unable to follow clinical protocol for the duration of the study or is otherwise deemed unacceptable to participate in the study per the investigator's clinical judgment