This feasibility study is a prospective, single arm study evaluating the Tandem Freedom system in adults with type 1 diabetes. Existing Control-IQ technology users will use Control-IQ technology at home for a 1 week run-in, then will use Tandem Freedom in a supervised hotel setting.

After a 1 week Control-IQ run-in at home, 10 adults who are existing Control-IQ users with type 1 diabetes will use the Tandem Freedom System for 1 day with boluses, and 1 day without boluses, in a supervised hotel setting. Participants will perform meal and exercise challenges. The primary outcome is safety events. CGM time in ranges will also be evaluated.

Inclusion Criteria:

• Age ≥18 years old
• Diagnosis of type 1 diabetes for at least 1 year
• Current Control-IQ user, having been prescribed Control-IQ for at least 3 months
• HbA1c ≤10%, recorded in the last 3 months
• Investigator has confidence that the participant can successfully operate all study devices and is capable of adhering to the protocol, including performing the weekend hotel observed setting portion of the study.
• Willing to use only aspart (novorapid) or lispro (humalog) insulin with the study pump, with no use of long-acting basal insulin injections, or inhaled insulin with the study pump.
• Have current glucagon product to treat severe hypoglycemia (injectable or nasal) at home (site will provide prescription if they do not have one)

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 Novorapid

• 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

10 adults with type 1 diabetes, who were existing users of the t:slim X2 insulin pump with Control-IQ technology for at least 3 months

9 days, to include a 7 day run-in with Control-IQ technology, followed by one day of Freedom with boluses and one day of Freedom without boluses.