The goal of this clinical trial is to assess safety of and explore glycemic outcomes with Control-IQ technology 2.0 in adults, children and preschoolers with type 1 diabetes.

This feasibility study is a prospective, randomized, two-period crossover multi-center study of Control-IQ technology 2.0. After a two week run-in period, the automated insulin dosing (AID) system will be evaluated in multiple age groups over 4 weeks of use.

Inclusion Criteria:

• Age 2 to ≤ 81 years
• Diagnosis of type 1 diabetes for at least 1 year, or at least 6 months for age 2-5 years at enrollment
• Prior Dexcom CGM user, with at least 11 of the prior 14 days of CGM use available for download at the screening visit to confirm eligibility
• Total Daily Insulin Dose (TDD) at least 2 units/day
• Weight ≥ 20 lbs
• HbA1c ≤ 10.5%
• For participants <18 years old, living with one or more parent/legal guardian knowledgeable about emergency procedures for severe hypoglycemia, present with the participant during and after the meal challenges, and willing to use the Dexcom Follow app (with push notifications turned on) for the duration of the study.
• For participants ≥18 years old, availability of a local contact who has access to the study participant, and willing to use the Dexcom Follow app (with push notifications turned on) for the duration of the study. If the participant lives alone, the local contact must live within 30 minutes and have access to the subject overnight.
• Investigator has confidence that the participant and/or parent/guardian can successfully operate all study devices and is capable of adhering to the protocol.
• Willing to use only aspart (novolog) or lispro (humalog) insulin with the study devices, with no use of long-acting basal insulin injections, or inhaled insulin with the study devices.
• Have current glucagon product to treat severe hypoglycemia (injectable or nasal) at home (site will provide prescription if they do not have one)
• Willing and able to perform study meal challenges.

Exclusion Criteria:

• More than 1 episode of diabetic ketoacidosis (DKA) in the past 6 months

• More than 1 episode of severe hypoglycemia (needing assistance) in the past 6 months

• Inpatient psychiatric treatment in the past 6 months

• 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
  2. Counseling on appropriate birth control options will be provided to all females of child-bearing potential

• 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).

• Hemophilia or any other bleeding disorder

• Hemoglobinopathy

• History of heart, liver, lung or kidney disease determined by investigator to interfere with the study

• History of allergic reaction to Humalog or Novolog

• Use of any medications determined by investigator to interfere with study

• Significant chronic kidney disease (which could impact CGM accuracy in investigator's judgment) or hemodialysis

• Concurrent use of any medication that could interfere with the study CGM, such as hydroxyurea

• History of adrenal insufficiency

• History of abnormal TSH consistent with hypothyroidism or hyperthyroidism that is not appropriately treated

• History of gastroparesis

• A condition, which in the opinion of the investigator or designee, would put the participant or study at risk

• Participation in another pharmaceutical or device trial at the time of enrollment or anticipated for during the time period of study participation

• 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

Two weeks for each intervention.