Extended Bolus for Meals in a Closed-loop System

Open to people ages 13-18

• Age between 13 and 18 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

• 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