The Pediatric Artificial Pancreas (PEDAP) Trial of Control-IQ Technology in Young Children in Type 1 Diabetes

Inclusion Criteria: 1. Clinical diagnosis, based on investigator assessment, of type 1 diabetes for at least 6 months and using insulin for at least 6 months 2. Familiarity and use of a carbohydrate ratio for meal boluses. 3. Age ≥2 and \<6 years old 4. Living with one or more parent/legal guardian knowledgeable about emergency procedures for severe hypoglycemia and able to contact emergency services and study staff. 5. Investigator has confidence that the parent can successfully operate all study devices and is capable of adhering to the protocol 6. Willingness to switch to lispro (Humalog) or aspart (Novolog) if not using already, and to use no other insulin besides lispro (Humalog) or aspart (Novolog) during the study for participants using a study-provided Tandem pump during the study. • Study will not be providing insulin; therefore, participants will need to have access to either lispro or aspart 7. Total daily insulin dose (TDD) at least 5 U/day 8. Body weight at least 20 lbs. 9. Willingness not to start any new non-insulin glucose-lowering agent during the course of the trial (see section 2.3) 10. Participant and parent(s)/guardian(s) willingness to participate in all training sessions as directed by study staff. 11. Parent/guardian proficient in reading and writing English. Exclusion Criteria: 1. Concurrent use of any non-insulin glucose-lowering agent (including Glucagon-like peptide-1 \[GLP-1\] agonists, Symlin, Dipeptidyl peptidase-4 \[DPP-4\] inhibitors, Sodium-glucose Cotransporter-2 (SGLT-2) inhibitors, sulfonylureas). 2. Hemophilia or any other bleeding disorder 3. History of \>1 severe hypoglycemic event with seizure or loss of consciousness in the last 3 months 4. History of \>1 DKA event in the last 6 months not related to illness, infusion set failure, or initial diagnosis 5. History of chronic renal disease or currently on hemodialysis 6. History of adrenal insufficiency 7. Hypothyroidism that is not adequately treated 8. Use of oral or injectable steroids within the last 8 weeks 9. Known, ongoing adhesive intolerance 10. Plans to receive blood transfusions or erythropoietin injections during the course of the study 11. A condition, which in the opinion of the investigator or designee, would put the participant or study at risk (specified in the study procedure manual) 12. Currently using any closed-loop system, or using an insulin pump that is incompatible with use of the study CGM 13. Participation in another pharmaceutical or device trial at the time of enrollment or during the study 14. Employed by, or having immediate family members employed by Tandem Diabetes Care, Inc., or having a direct supervisor at place of employment who is also directly involved in conducting the clinical trial (as a study investigator, coordinator, etc.); or having a first-degree relative who is directly involved in conducting the clinical trial