Intermittent Fasting in Adults With Type 1 Diabetes

February 26, 2026 updated by: Krista Varady, University of Illinois at Chicago
The majority of adults with type 1 diabetes (T1DM) have either overweight or obesity. As such, dietary management has been recommended as an adjunct to insulin treatment to improve glycemic control and facilitate weight loss in patients with T1DM. Daily calorie restriction (CR) is the main diet prescribed to patients with T1DM for weight loss. However, many patients find it difficult to adhere to CR because calorie intake must be vigilantly monitored every day. In light of these problems with CR, another approach that limits timing of food intake, instead of number of calories consumed, has been developed. This diet is called "time restricted eating" (TRE) and involves confining the period of food intake to 6-8 h per day. TRE allows individuals to self-select foods and eat ad libitum during a large part of the day, which greatly increases compliance to these protocols. The simplicity of TRE, its accommodation of dietary preferences, and associated weight loss may translate to improved glycemic measures in patients with T1DM. The present study will be the first randomized controlled trial to compare the effect of TRE versus CR for weight management and improved glycemic control in adults with obesity and T1DM.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
32

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.
  • Name: Krista Varady, PhD
  • Phone Number: 3129967897
  • Email: varady@uic.edu

Study Locations

  • United States
    • Illinois
      • Chicago, Illinois, United States, 60612
        • University of Illinois Chicago

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Previously diagnosed with T1DM and currently using insulin
  • HbA1c: 6.5-9.5% (regardless of medication use)
  • Age between 18 to 75 years old
  • BMI between 25 and 50 kg/m2
  • Independently living (i.e., subjects who do not live in a nursing home or institution)
  • On either multiple daily doses of insulin injections (MDII) or using an insulin pump (with or without closed loop feature)
  • Active prescription for daily use of a continous glucose monitor (CGM) or willing to be provided with a CGM during the study (at no cost)
  • Active prescription for glucagon

Exclusion Criteria:

  • History of severe hypoglycemia defined as requiring help from others, needed to use emergency glucagon administration in the past 6 months.
  • Medical history of heart failure, unstable coronary artery disease, chronic obstructive pulmonary disease, requiring oxygen, cirrhosis, active cancer, history of stroke, cognitive impairment, end stage renal disease (eGFR ≤30 ml/min/m2)
  • Previously diagnosed with T2DM
  • Have a history of eating disorders (anorexia, bulimia, or binge eating disorder)
  • Are not weight stable for 3 months prior to the beginning of study (weight gain or loss > 4%)
  • Are not able to keep a food diary for 7 consecutive days during screening
  • Are taking certain drugs that have significant weight loss outcomes (weight loss medications, specifically GLP1 agonist, GLP-1/GIP agonists)
  • Are eating less than a 10-hour window at baseline
  • Are perimenopausal (menses does not appear every 27-32d)
  • Are pregnant, or trying to become pregnant
  • Are night shift workers

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Daily calorie restriction (CR)
25% energy restriction every day Diet counseling provided
Other: Daily calorie restriction
25% energy restriction every day Diet counseling provided
No Intervention: Control
Ad libitum food intake, eating over more than 10 hours per day
Experimental: Time restricted eating (TRE)
8-h eating window Ad libitum food intake from 12-8 pm every day Fasting from 8-12 pm every day (16-h fast)
Other: Time restricted eating
8-h eating window Ad libitum food intake from 12-8 pm every day Fasting from 8-12 pm every day (16-h fast)

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Change in percent body weight
Time Frame: Measured at baseline and month 6
Measured by an electronic scale
Measured at baseline and month 6

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change in total time in euglycemic range
Time Frame: Measured at baseline and month 6
Measured by continuous glucose monitor (CGM)
Measured at baseline and month 6
Change in mean glucose level
Time Frame: Measured at baseline and month 6
Measured by continuous glucose monitor (CGM)
Measured at baseline and month 6
Change in standard deviation of glucose level
Time Frame: Measured at baseline and month 6
Measured by continuous glucose monitor (CGM)
Measured at baseline and month 6
Change in fat mass, lean mass, visceral fat mass
Time Frame: Measured at baseline and month 6
Measured by DXA
Measured at baseline and month 6
Change in waist circumference
Time Frame: Measured at baseline and month 6
Measured by measuring tape
Measured at baseline and month 6
Change in body mass index (BMI)
Time Frame: Measured at baseline and month 6
Calculated as kg/meter squared
Measured at baseline and month 6
Change in systolic and diastolic blood pressure
Time Frame: Measured at baseline and month 6
Measured by blood pressure cuff
Measured at baseline and month 6
Change in heart rate
Time Frame: Measured at baseline and month 6
Measured by blood pressure cuff
Measured at baseline and month 6
Change in energy and nutrient intake
Time Frame: Measured at baseline and month 6
Measured by 7-day food record
Measured at baseline and month 6
Change in coefficient of variation of glucose level
Time Frame: Measured at baseline and month 6
Measured by continuous glucose monitor (CGM)
Measured at baseline and month 6
Change in absolute body weight
Time Frame: Measured at baseline and month 6
Measured by an electronic scale
Measured at baseline and month 6
Change in dietary adherence
Time Frame: Measured at baseline and month 6
Measured by 7-day food record and adherence log
Measured at baseline and month 6
Change in physical activity (steps/d)
Time Frame: Measured at baseline and month 6
Measured by activity monitor
Measured at baseline and month 6
Change in HbA1c
Time Frame: Measured at baseline and month 6
Measured by ELISA
Measured at baseline and month 6
Change in plasma lipids (total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides)
Time Frame: Measured at baseline and month 6
Measured using enzymatic kits, standardized reagents, and standardsand analyzed using a microplate reader
Measured at baseline and month 6
Adverse events
Time Frame: Measured at baseline and month 6
Measured by adverse events survey and continous glucose monitor (for events of hypoglycemia and hyperglycemia)
Measured at baseline and month 6
Change in insulin dose
Time Frame: Measured at baseline and month 6
Measured by recording total insulin dose, basal insulin dose, and bolus insulin dose
Measured at baseline and month 6

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Illinois at Chicago

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Krista Varady, PhD, University of Illinois Chicago

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
November 20, 2023

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
September 1, 2025

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
September 1, 2025

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 11, 2023

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 11, 2023

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 18, 2023

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
March 2, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 26, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
February 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 2023-0678

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

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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