Using extended insulin boluses to improve glucose control in type 1 diabetes

Postprandial Glucose Control Using an Extended Bolus for High-fat High Protein Meals in a Closed-loop System in Patients With Type 1 Diabetes

Phase 4 Interventional University of California, San Francisco · NCT05454891

This study is testing if giving insulin in a special way during high-fat, high-protein meals can help teenagers with type 1 diabetes keep their blood sugar levels more stable.

Quick facts

PhasePhase 4
Study typeInterventional
Enrollment30 (estimated)
Ages13 Years to 19 Years
SexAll
SponsorUniversity of California, San Francisco Academic / other
Locations1 site (San Francisco, California)
Trial IDNCT05454891 on ClinicalTrials.gov

What this trial studies

This study evaluates the effectiveness of an extended bolus of insulin in managing glucose levels during high-fat, high-protein meals in adolescents with type 1 diabetes using a closed-loop system. Participants will receive either an extended bolus followed by a standard bolus or vice versa to determine which method provides better glucose control. The goal is to reduce the risk of prolonged hyperglycemia or early hypoglycemia by optimizing insulin delivery over an extended period. The study will involve participants aged 13 to 19 who are currently using the Control IQ closed-loop system.

Who should consider this trial

Good fit: Ideal candidates are adolescents aged 13 to 19 with type 1 diabetes, an A1C greater than 6%, and currently using a Control IQ closed-loop system.

Not a fit: Patients with an A1C greater than 10% or recent severe hypoglycemia or diabetic ketoacidosis may not benefit from this study.

Why it matters

Potential benefit: If successful, this approach could lead to improved glucose management for adolescents with type 1 diabetes, particularly during challenging meal scenarios.

How similar studies have performed: Other studies have explored insulin delivery methods in diabetes management, but this specific approach using extended boluses in a closed-loop system is relatively novel.

Eligibility criteria

Show full inclusion / exclusion criteria
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

Where this trial is running

San Francisco, California

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Type 1 Diabetes
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.