Type 1 DiabetesNCT05454891
Extended Bolus for Meals in a Closed-loop System
A study testing Tandem t:slim X2 insulin pump: Extended bolus of insulin then standard bolus of insulin and Tandem t:slim X2 insulin pump: Standard bolus of insulin then extended bolus of insulin in people with Type 1 Diabetes, run by University of California, San Francisco at 1 site in United States.
Trial summary
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… Read more about this study
- Who is it for?
- Ages 13 to 19 years
- Conditions the study is for
- Type 1 Diabetes
- What is being tested?
- Tandem t:slim X2 insulin pump: Extended bolus of insulin then standard bolus of insulin and Tandem t:slim X2 insulin pump: Standard bolus of insulin then extended bolus of insulin
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 30 participants
- Where
- 1 siteUnited States
- Study dates
- 15 Jul 2022to 19 Dec 2024
- Phase
- Interventional
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 13 to 19 years
- All sexes
- No healthy volunteers
- Child, Adult
Who may be able to join
- 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
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- 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
Who cannot join
- 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
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- 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
Trial locations and contacts
1 site in 1 country.
United States1 site
University of California San Francisco
San Francisco, California, 94158
About this study
Official title: 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.
- Conditions
- Type 1 Diabetes
- Being tested
- Tandem t:slim X2 insulin pump: Extended bolus of insulin then standard bolus of insulin, Tandem t:slim X2 insulin pump: Standard bolus of insulin then extended bolus of insulin
- Medical subject headings
- Diabetes Mellitus, Type 1
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Tandem t:slim X2 insulin pump: Extended bolus of insulin then standard bolus of insulinDevice
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.
Tandem t:slim X2 insulin pump: Standard bolus of insulin then extended bolus of insulinDevice
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.
| Study group | Role | What they receive |
|---|---|---|
| High Fat High Protein (HFHP) Meal- extended then standard insulin bolus arm | Experimental | Subjects will receive extended meal bolus for breakfast on the first day and standard meal bolus on the second day of the study. Receives: Device: Tandem t:slim X2 insulin pump: Extended bolus of insulin then standard bolus of insulin |
| High Fat High Protein (HFHP) Meal- standard then extended insulin bolus arm | Experimental | Subjects will receive standard meal bolus for breakfast on the first day and extended meal bolus on the second day. Receives: Device: Tandem t:slim X2 insulin pump: Standard bolus of insulin then extended bolus of insulin |
What is being measured
The primary outcome is the main question the study is designed to answer.
Glucose Area Under Curve [AUC]
Area under the curve between glucose trace and starting glucose (mg/dL* min)
Measured: 0 to 5 hours post-meal onset
Secondary outcomes (11)
Percentage of Time Between 70-180 mg/dL
Percentage of time spent between 70-180 mg/dl based on Continuous Glucose Monitor (CGM) values
Measured: 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
Measured: 0 to 5 hours post-meal onset
Average Glucose
Average glucose value based on Continuous Glucose Monitor (CGM) values
Measured: 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
Measured: 0 to 5 hours post-meal onset
Insulin Dosage
Total insulin received during 5 hrs ( manual bolus as well as automated)
Measured: 0 to 5 hours post-meal onset
Time to Target (110mg/dL)
Time spent till blood glucose returns to 110mg/dL
Measured: 0 to 5 hours post-meal onset
Time to Baseline
Time spent till blood glucose returns to baseline
Measured: 0 to 5 hours post-meal onset
Time to Peak Glucose
Time spent till blood glucose reaches the maximum value after meal
Measured: 0 to 5 hours post-meal onset
Change in Glucose
The difference between baseline to max glucose value
Measured: 0 to 5 hours post-meal onset
Peak Glucose Concentration
Max blood glucose
Measured: 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
Measured: 0 to 5 hours post-meal onset
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted12 Jul 2022
- Study start15 Jul 2022
- Primary completion19 Dec 2024
- Study completion19 Dec 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Other trials for Type 1 DiabetesStudies of the same condition, open and under way.
- More trials run by University of California, San FranciscoThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Participants will be randomly assigned (1:1) in blocks of two to the order in which they receive the two premeal insulin boluses: extended followed by standard bolus or a standard followed by extended bolus.
- Masking
- None (open label)
- Enrolment
- 30 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of California, San Francisco
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Laya Ekhlaspour, MD, Principal investigator, University of California, San Francisco
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05454891
- Sponsor's protocol ID
- 58992
- Other IDs
- 5K23DK121942-02
- Status last verified
- Apr 2026
- First submitted
- 24 Jun 2022
- Last updated
- 12 May 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- Yes
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 12 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Postprandial Glucose Control Using an Extended Bolus for High-fat High Protein Meals in a Closed-loop System in Patients With Type 1 Diabetes
- ClinicalTrials.gov ID
- NCT05454891
- Acronym / sponsor ID
- 58992
- Conditions
- Type 1 Diabetes
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 30 participants (actual)
- Lead sponsor
- University of California, San FranciscoUniversity, hospital or other
- Collaborators
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
- Study start
- 15 Jul 2022 (actual)
- Primary completion
- 19 Dec 2024 (actual)
- Study completion
- 19 Dec 2024 (actual)
- First posted
- 12 Jul 2022 (actual)
- Results
- Posted 12 May 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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 design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- Participants will be randomly assigned (1:1) in blocks of two to the order in which they receive the two premeal insulin boluses: extended followed by standard bolus or a standard followed by extended bolus.
| Arm | Type | Receives |
|---|---|---|
| High Fat High Protein (HFHP) Meal- extended then standard insulin bolus arm | Experimental | Device: Tandem t:slim X2 insulin pump: Extended bolus of insulin then standard bolus of insulinSubjects will receive extended meal bolus for breakfast on the first day and standard meal bolus on the second day of the study. |
| High Fat High Protein (HFHP) Meal- standard then extended insulin bolus arm | Experimental | Device: Tandem t:slim X2 insulin pump: Standard bolus of insulin then extended bolus of insulinSubjects will receive standard meal bolus for breakfast on the first day and extended meal bolus on the second day. |
Who may qualify
- Ages
- 13 to 19 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult
Key inclusion criteria (11 listed)
- 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
Key exclusion criteria (12 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Tandem t:slim X2 insulin pump: Extended bolus of insulin then standard bolus of insulinFor 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. | Device | High Fat High Protein (HFHP) Meal- extended then standard insulin bolus arm |
| Tandem t:slim X2 insulin pump: Standard bolus of insulin then extended bolus of insulinFor 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. | Device | High Fat High Protein (HFHP) Meal- standard then extended insulin bolus arm |
Primary outcome
Glucose Area Under Curve [AUC]
Time frame: 0 to 5 hours post-meal onset
Area under the curve between glucose trace and starting glucose (mg/dL* min)
11 secondary outcomes
Percentage of Time Between 70-180 mg/dL
Time frame: 0 to 5 hours post-meal onset
Percentage of Time in Hypoglycemic Range (Defined as < 70 mg/dL)
Time frame: 0 to 5 hours post-meal onset
Average Glucose
Time frame: 0 to 5 hours post-meal onset
Percentage of Time in Hyperglycemic Range (Defined as ≥180 mg/dL);
Time frame: 0 to 5 hours post-meal onset
Insulin Dosage
Time frame: 0 to 5 hours post-meal onset
Time to Target (110mg/dL)
Time frame: 0 to 5 hours post-meal onset
Time to Baseline
Time frame: 0 to 5 hours post-meal onset
Time to Peak Glucose
Time frame: 0 to 5 hours post-meal onset
Change in Glucose
Time frame: 0 to 5 hours post-meal onset
Peak Glucose Concentration
Time frame: 0 to 5 hours post-meal onset
Percentage of Time Between 70-140 mg/dL
Time frame: 0 to 5 hours post-meal onset
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 12 May 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Laya Ekhlaspour, MD principal investigator
University of California, San Francisco
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Tandem t:slim X2 insulin pump: Extended bolus of insulin then standard bolus of insulin and Tandem t:slim X2 insulin pump: Standard bolus of insulin then extended bolus of insulin in people with Type 1 Diabetes, run by University of California, San Francisco at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 11 inclusion and 12 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 12 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
Yes. Results are posted in the registry (first posted 12 May 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Glucose Area Under Curve [AUC] (time frame: 0 to 5 hours post-meal onset). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 12 May 2026.