Extended Bolus for Meals in a Closed-loop System

Inclusion Criteria

• Age between 13 and 19 years old, A1C > 6% at screening

• Diagnosed with type 1 diabetes for at least one year

• Total daily dose (TDD) of insulin ≥ 0.3 units/kg/day

• Currently using the Control IQ closed-loop system

• Willing to abide by meal recommendations and study procedures

• Willing and able to sign the Informed Consent Form (ICF) and/or has a parent or guardian willing and able to sign the ICF

• Use an Android or Apple smartphone

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

• Participant and parent(s)/guardian(s) willingness to participate in all training sessions as directed by study staff

• Parent/guardian proficient in reading and writing English

• Live in the United States, with no plans to move outside the United States during the study period

Exclusion Criteria

• A1C >10%

• One or more episodes of severe hypoglycemia or DKA requiring ER visit or hospitalization within the past three months

• Used non-insulin anti-diabetic medication within the last 30 days other than metformin

• Known history of gastroparesis, seizure disorder, adrenal insufficiency, or ongoing renal or hepatic disease

• Pregnancy or lactation

• Untreated or unstable hypothyroidism

• Currently undergoing cancer treatment or systemic treatment with steroids

• Untreated or inadequately treated mental illness

• Current alcohol abuse

• Current illness that would interfere with participation in the study

• Delayed gastric emptying or any concurrent conditions that can be associated with delayed gastric emptying or altered digestion; and the use of any medication that affects gastric emptying

• Celiac Disease