Safety Evaluation of an Advanced Hybrid Closed Loop System Using Lyumjev With the Tandem t:Slim X2 Insulin Pump With Control-IQ Technology in Adults, Adolescents and Children With Type 1 Diabetes

Inclusion Criteria: 1. Age 6 to \<81 years 2. Diagnosis of type 1 diabetes for at least 1 year 3. Currently using Control-IQ technology for at least 3 months, with CGM data recorded indicative of system use (active closed loop) for at least 85% of the possible time in 14 days prior to enrollment 4. Total daily insulin dose (TDD) at least 2 U/day 5. HbA1c \< 10.5% 6. Residing full-time in the United States, with no anticipated travel outside the United States during the period of study participation. 7. For participants \<18 years old, living with one or more parent/legal guardian knowledgeable about emergency procedures for severe hypoglycemia and able to contact the participant in case of an emergency, and willing to use the Dexcom Follow app (with push notifications turned on) for the duration of the study. 8. If \>18 years old, participant has someone who lives within 30 minutes of them who is willing to be contacted if the study team can't reach the participant in case of a suspected medical emergency. 9. Participant has agreed to participate in the study; and has read, understood and signed the informed consent form (ICF) and assent, if applicable; and has agreed to follow all study procedures, including: 1. suspending use of any personal CGM for the duration of the clinical trial once the study CGM is in use 2. switching to or continuing to use Humalog during the lead-in period 3. switching to Lyumjev for the main study period. 4. willing and able to perform the study exercise and meal challenges. 10. Investigator has confidence that the participant can successfully operate all study devices and is capable of adhering to the protocol, including ability to respond to alerts and alarms, and to provide basic diabetes self-management. 11. Participant and/or parent/legal guardian have the ability to read and understand English Exclusion Criteria: 1. More than 1 episode of diabetic ketoacidosis (DKA) in the past 6 months 2. More than 1 episode of severe hypoglycemia (needing assistance) in the past 6 months 3. Inpatient psychiatric treatment in the past 6 months 4. History of drug abuse (defined as any illicit drug use) or history of alcohol abuse prior to screening or unwillingness to agree to abstain from illicit drugs throughout the study. 5. For Female: Currently pregnant or planning to become pregnant during the time period of study participation 1. A negative pregnancy test will be required for all females of child-bearing potential (menarchal) 2. Counseling on appropriate birth control options will be provided to females with child-bearing potential in the event the participant does not have an acceptable plan. 6. Adults lacking the capacity to provide consent and/or follow study procedures in the opinion of the investigator 7. Concurrent use of any non-insulin glucose-lowering agent, other than metformin (for example, GLP-1 agonists, Symlin, DPP-4 inhibitors, SGLT-2 inhibitors, sulfonylureas). 8. Hemophilia or any other bleeding disorder 9. Hemoglobinopathy 10. History of heart, liver, lung or kidney disease determined by investigator to interfere with the study 11. History of allergic reaction to Humalog or Lyumjev 12. Use of glucocorticoids, beta blockers or other medications determined by investigator to interfere with study 13. Abnormal screening electrocardiogram consistent with increased risk during exercise, such as arrhythmia, ischemia, or prolonged QTc interval (\>450 ms) (Screening ECG only required for participants age \> 50 years, duration of diabetes \> 20 years, or history of coronary artery disease) 14. Significant chronic kidney disease (which could impact CGM accuracy in investigator's judgment) or hemodialysis 15. History of adrenal insufficiency 16. History of abnormal TSH consistent with hypothyroidism or hyperthyroidism that is not appropriately treated 17. History of gastroparesis 18. A condition, which in the opinion of the investigator or designee, would put the participant or study at risk 19. Participation in another pharmaceutical or device trial at the time of enrollment or anticipated for during the time period of study participation 20. Employed by, or having immediate family members employed by Tandem Diabetes Care, Inc., Eli Lilly and Co., or TypeZero Technologies, LLC, 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