Extended Bolus for Meals in a Closed-loop System

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

This study aims to evaluate whether the use of an extended bolus will improve glucose control with high-fat high protein meals using a closed-loop system. The new knowledge gained from this study may provide a method to allow for the proper administration of insulin over an extended period to mitigate the risk of prolonged hyperglycemia or early hypoglycemia.

Study Overview

• Status: Completed
• Conditions: Type 1 Diabetes
• Intervention / Treatment: Device: Tandem t:slim X2 insulin pump: Extended bolus of insulin then standard bolus of insulin; Device: Tandem t:slim X2 insulin pump: Standard bolus of insulin then extended bolus of insulin

• Study Type: Interventional
• Enrollment (Actual): 30
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • California
    • San Francisco, California, United States, 94158
      • University of California San Francisco

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 13 years to 18 years (Child, Adult)
• Accepts Healthy Volunteers: No

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: High Fat High Protein (HFHP) Meal- extended then standard insulin bolus arm; Subjects will receive extended meal bolus for breakfast on the first day and standard meal bolus on the second day of the study.	Device: Tandem t:slim X2 insulin pump: Extended bolus of insulin then standard bolus of insulin; For a standardized HFHP breakfast, participants will receive an extended meal bolus of insulin on the first morning and a standard meal bolus of insulin on the second morning of the study.
Experimental: High Fat High Protein (HFHP) Meal- standard then extended insulin bolus arm; Subjects will receive standard meal bolus for breakfast on the first day and extended meal bolus on the second day.	Device: Tandem t:slim X2 insulin pump: Standard bolus of insulin then extended bolus of insulin; For a standardized HFHP breakfast, participants will receive a standard bolus of insulin on the first morning and an extended bolus of insulin on the second morning of the study.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Glucose Area Under Curve [AUC]	Area under the curve between glucose trace and starting glucose (mg/dL* min)	0 to 5 hours post-meal onset

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percentage of Time Between 70-180 mg/dL	Percentage of time spent between 70-180 mg/dl based on Continuous Glucose Monitor (CGM) values	0 to 5 hours post-meal onset
Percentage of Time in Hypoglycemic Range (Defined as < 70 mg/dL)	Percentage of time spent with blood sugar less than 70 mg/dL based on Continuous Glucose Monitor (CGM) values	0 to 5 hours post-meal onset
Average Glucose	Average glucose value based on Continuous Glucose Monitor (CGM) values	0 to 5 hours post-meal onset
Percentage of Time in Hyperglycemic Range (Defined as ≥180 mg/dL);	Percentage of time spent with blood sugar higher than 180 mg/dL based on Continuous Glucose Monitor (CGM) values	0 to 5 hours post-meal onset
Insulin Dosage	Total insulin received during 5 hrs ( manual bolus as well as automated)	0 to 5 hours post-meal onset
Time to Target (110mg/dL)	Time spent till blood glucose returns to 110mg/dL	0 to 5 hours post-meal onset
Time to Baseline	Time spent till blood glucose returns to baseline	0 to 5 hours post-meal onset
Time to Peak Glucose	Time spent till blood glucose reaches the maximum value after meal	0 to 5 hours post-meal onset
Change in Glucose	The difference between baseline to max glucose value	0 to 5 hours post-meal onset
Peak Glucose Concentration	Max blood glucose	0 to 5 hours post-meal onset
Percentage of Time Between 70-140 mg/dL	Percent of glucose readings from CGM system between 70-140 mg/dL per unit of time	0 to 5 hours post-meal onset

Collaborators and Investigators

• Sponsor: University of California, San Francisco
• Collaborators: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
• Investigators: Principal Investigator: Laya Ekhlaspour, MD, University of California, San Francisco

Study record dates

Study Major Dates

• Study Start (Actual): July 15, 2022
• Primary Completion (Actual): December 19, 2024
• Study Completion (Actual): December 19, 2024

Study Registration Dates

• First Submitted: June 24, 2022
• First Submitted That Met QC Criteria: July 8, 2022
• First Posted (Actual): July 12, 2022

Study Record Updates

• Last Update Posted (Actual): May 12, 2026
• Last Update Submitted That Met QC Criteria: April 20, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Endocrine System Diseases; Metabolic Diseases; Autoimmune Diseases; Immune System Diseases; Glucose Metabolism Disorders; Diabetes Mellitus; Nutritional and Metabolic Diseases; Diabetes Mellitus, Type 1; Physiological Effects of Drugs; Hypoglycemic Agents; Insulin; Insulin, Globin Zinc
• Other Study ID Numbers: 58992; 5K23DK121942-02 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No