Inclusion Criteria:

   1. Successful completion of the original 6-month RCT within the prior 14 days

   2. For females, not currently known to be pregnant. If female and sexually active, must
   agree to use a form of contraception to prevent pregnancy while a participant in the
   study. A negative urine pregnancy test will be required for all females of
   child-bearing potential. Participants who become pregnant will be discontinued from
   the study. Also, participants who during the study develop and express the intention
   to become pregnant within the timespan of the study will be discontinued.

   3. 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.

   4. Willingness to not use a personal CGM for the duration of the study

   5. Investigator has confidence that the participant can successfully operate all study
   devices and is capable of adhering to the protocol

   6. Willingness to use only lispro (Humalog) or aspart (Novolog), and to use no other
   insulin during the study.

   7. Willingness not to start any new non-insulin glucose-lowering agent during the course
   of the trial

Exclusion Criteria

   1. Concurrent use of any non-insulin glucose-lowering agent other than metformin
   (including GLP-1 agonists, Symlin, DPP-4 inhibitors, SGLT-2 inhibitors,
   sulfonylureas).

   2. Hemophilia or any other bleeding disorder

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

   4. Participation in another pharmaceutical or device trial at the time of enrollment or
   during the study

   5. Employed by, or having immediate family members employed by Tandem Diabetes Care,
   Inc., Dexcom, Inc., 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