Two-Year Weight Loss With GLP-1 Medications Compared With Sleeve Gastrectomy in Adults With Obesity (GLP-BARI-VAN)

November 3, 2026 updated by: Sebahattin Celik MD, Yuzuncu Yil University

Comparison of Two-Year Weight-Loss Effectiveness of GLP-1 Receptor Agonists and Laparoscopic Sleeve Gastrectomy in the Treatment of Obesity: An Ambispective Propensity Score-Matched Cohort Study

This observational study will compare weight loss over two years in adults receiving GLP-1 receptor agonist medications with weight loss in adults who previously underwent laparoscopic sleeve gastrectomy, an operation that reduces the size of the stomach.

Adults starting GLP-1 medications as part of their usual care will be followed for 24 months. Their results will be compared with existing medical records of adults who underwent sleeve gastrectomy at the same center. Treatment decisions will be made by patients and their treating clinicians as part of routine care, rather than assigned by the study.

The main outcome is the percentage of starting body weight lost at 24 months. The study will also assess weight changes at earlier visits, medication side effects, treatment continuation and reasons for stopping treatment, and changes in weight-related health conditions. The groups will be matched using baseline characteristics to make the comparison more balanced.

Study Overview

Status

Status

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

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.
Observational

Enrollment (Estimated)

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.
200

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.

Study Locations

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

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

Adults aged 18 years or older receiving treatment for obesity or overweight at the Obesity Center of Van Training and Research Hospital, Türkiye. The prospective cohort will include consecutive eligible patients initiating GLP-1 receptor agonist therapy for weight management as part of routine clinical care. The retrospective cohort will include eligible patients who underwent primary laparoscopic sleeve gastrectomy for obesity at the same center between January 1, 2020, and January 1, 2026. Treatment decisions are made independently of study participation. The cohorts will be matched using propensity scores based on pretreatment demographic and clinical characteristics.

Description

Inclusion Criteria:

GLP-1 Receptor Agonist Cohort:

  • Age 18 years or older at treatment initiation.
  • Initiation of a GLP-1 receptor agonist for obesity or overweight as part of routine clinical care.
  • Available baseline height and body weight measurements.
  • Willingness to attend at least one follow-up assessment.
  • Ability to comply with the center's standard follow-up program.
  • Provision of written informed consent.

Laparoscopic Sleeve Gastrectomy Cohort:

  • Age 18 years or older at surgery.
  • Primary laparoscopic sleeve gastrectomy for obesity performed at the study center between January 1, 2020, and January 1, 2026.
  • Available preoperative height, body weight, and body mass index measurements.
  • Available demographic and baseline clinical data.
  • At least one documented postoperative body weight measurement. Availability of a 24-month weight measurement is preferred for the primary comparison.

Exclusion Criteria:

Both Cohorts:

  • Bariatric or metabolic surgery before the index treatment.
  • Revisional bariatric surgery as the index treatment.
  • Active malignancy or a serious systemic disease substantially affecting body weight.
  • Pregnancy or breastfeeding at the index treatment.
  • Uncontrolled endocrine disease that may cause weight loss.
  • Missing baseline height or body weight measurements.
  • Recent participation in another intensive weight-loss program before the index treatment.
  • Concurrent use of another anti-obesity treatment that could substantially affect study outcomes.
  • Inability to reliably verify study data.

GLP-1 Receptor Agonist Cohort:

  • Short-term GLP-1 receptor agonist use for an indication other than weight management.
  • Medication prescribed but never administered.

Laparoscopic Sleeve Gastrectomy Cohort:

  • Sleeve gastrectomy performed concurrently with another bariatric procedure.
  • Sleeve gastrectomy performed for an indication other than primary obesity treatment.

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

  • Observational Models: COHORT
  • Time Perspectives: OTHER

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
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.
GLP-1 Receptor Agonist Cohort

Adults aged 18 years or older starting a GLP-1 receptor agonist, such as liraglutide or semaglutide, for weight management as part of routine clinical care. Participants will be followed prospectively for 24 months, with assessments at baseline and months 1, 3, 6, 12, and 24. Weight changes, medication use, treatment adherence, adverse events, and treatment discontinuation will be recorded. Medication selection and dosing will be determined by the treating clinician independently of study participation.
Drug: GLP-1 Receptor Agonist Therapy

GLP-1 receptor agonists, such as liraglutide or semaglutide, prescribed for weight management as part of routine clinical care. Medication selection, dose escalation, dose adjustment, and treatment discontinuation are determined by the treating clinician and are not assigned by the study protocol. Medication use, weight changes, treatment adherence, and adverse events will be recorded during 24 months of prospective follow-up.

Other Names:
  • Glucagon-Like Peptide-1 Receptor Agonist Therapy
Laparoscopic Sleeve Gastrectomy Cohort

Adults who underwent primary laparoscopic sleeve gastrectomy for obesity at the same center between January 1, 2020, and January 1, 2026, and were aged 18 years or older at surgery. Existing medical records will be reviewed retrospectively for baseline characteristics, postoperative weight measurements through 24 months, and surgical complications. This cohort will be matched with the GLP-1 receptor agonist cohort using propensity scores based on pretreatment characteristics. Surgery was performed as part of routine clinical care independently of this study.
Procedure: Laparoscopic Sleeve Gastrectomy

Primary laparoscopic sleeve gastrectomy performed for obesity as part of routine clinical care between January 1, 2020, and January 1, 2026. The procedure involves removing a large portion of the stomach to create a narrow, sleeve-shaped stomach. Existing medical records will be reviewed retrospectively to assess weight changes and surgical complications through 24 months after surgery.

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
Percentage of Total Body Weight change at 24 Months
Time Frame: 24 months after GLP-1 receptor agonist treatment initiation or sleeve gastrectomy.

Percentage of total body weight loss (%TWL), calculated as [(baseline body weight - body weight at 24 months) / baseline body weight] × 100. Baseline is the date of GLP-1 receptor agonist treatment initiation or sleeve gastrectomy. The outcome will be compared between the propensity score-matched treatment cohorts.
24 months after GLP-1 receptor agonist treatment initiation or sleeve gastrectomy.

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
Percentage of Total Body Weight change at Earlier Follow-Up Visits
Time Frame: At 1, 3, 6, and 12 months after treatment initiation.

Percentage of total body weight loss (%TWL), calculated as [(baseline body weight - follow-up body weight) / baseline body weight] × 100, compared between the treatment cohorts.
At 1, 3, 6, and 12 months after treatment initiation.
Change in Body Weight
Time Frame: Baseline to months 1, 3, 6, 12, and 24.

Change in body weight from baseline, measured in kilograms, compared between the treatment cohorts.
Baseline to months 1, 3, 6, 12, and 24.
Change in Body Mass Index
Time Frame: Baseline to months 1, 3, 6, 12, and 24.

Change in body mass index (BMI) from baseline, calculated as body weight in kilograms divided by height in meters squared, compared between the treatment cohorts.
Baseline to months 1, 3, 6, 12, and 24.
Percentage of Participants Achieving at Least 5% Total Body Weight Loss
Time Frame: At months 1, 3, 6, 12, and 24.

Percentage of participants losing at least 5% of their baseline body weight, compared between the treatment cohorts.
At months 1, 3, 6, 12, and 24.
Percentage of Participants Achieving at Least 10% Total Body Weight Loss
Time Frame: At months 1, 3, 6, 12, and 24.

Percentage of participants losing at least 10% of their baseline body weight, compared between the treatment cohorts.
At months 1, 3, 6, 12, and 24.
Percentage of Participants Achieving at Least 15% Total Body Weight Loss
Time Frame: At months 1, 3, 6, 12, and 24.

Percentage of participants losing at least 15% of their baseline body weight, compared between the treatment cohorts.
At months 1, 3, 6, 12, and 24.
Percentage of Participants Achieving at Least 20% Total Body Weight Loss
Time Frame: At months 1, 3, 6, 12, and 24.

Percentage of participants losing at least 20% of their baseline body weight, compared between the treatment cohorts.
At months 1, 3, 6, 12, and 24.
Percentage of Participants Achieving at Least 25% Total Body Weight Loss
Time Frame: At months 1, 3, 6, 12, and 24.

Percentage of participants losing at least 25% of their baseline body weight, compared between the treatment cohorts.
At months 1, 3, 6, 12, and 24.
Percentage of Participants Experiencing Any Adverse Event During GLP-1 Therapy
Time Frame: From the first medication dose through 24 months.

Percentage of participants in the GLP-1 receptor agonist cohort experiencing at least one adverse event. Event type, onset, severity, and suspected relationship to medication will be recorded.
From the first medication dose through 24 months.
Percentage of Participants Experiencing Gastrointestinal Adverse Events During GLP-1 Therapy
Time Frame: From the first medication dose through 24 months.

Percentage of participants in the GLP-1 receptor agonist cohort experiencing gastrointestinal adverse events, including nausea, vomiting, diarrhea, constipation, abdominal pain, or reflux/dyspepsia.
From the first medication dose through 24 months.
Percentage of Participants Experiencing Serious Adverse Events During GLP-1 Therapy
Time Frame: From the first medication dose through 24 months.

Percentage of participants in the GLP-1 receptor agonist cohort experiencing an adverse event resulting in death, a life-threatening condition, inpatient hospitalization or prolonged hospitalization, persistent or significant disability, a congenital anomaly, or another medically important event.
From the first medication dose through 24 months.
Percentage of Participants Requiring GLP-1 Dose Reduction Due to Adverse Events
Time Frame: From treatment initiation through 24 months.

Percentage of participants in the GLP-1 receptor agonist cohort whose medication dose is reduced because of an adverse event.
From treatment initiation through 24 months.
Percentage of Participants Permanently Discontinuing GLP-1 Therapy Due to Adverse Events
Time Frame: From treatment initiation through 24 months.

Percentage of participants in the GLP-1 receptor agonist cohort who permanently discontinue medication because of an adverse event.
From treatment initiation through 24 months.
Percentage of Participants Permanently Discontinuing GLP-1 Therapy for Any Reason
Time Frame: From treatment initiation through 24 months.

Percentage of participants in the GLP-1 receptor agonist cohort who permanently discontinue medication for any reason. Reasons for discontinuation will be recorded.
From treatment initiation through 24 months.
Duration of GLP-1 Treatment Persistence
Time Frame: From treatment initiation through 24 months.

Time in months from GLP-1 receptor agonist treatment initiation to permanent discontinuation. Participants without permanent discontinuation will be censored at their last known follow-up or the end of the 24-month observation period.
From treatment initiation through 24 months.
Improvement or Remission of Obesity-Related Comorbidities
Time Frame: At months 3, 6, 12, and 24.

Percentage of participants with improvement or remission of baseline obesity-related comorbidities, including type 2 diabetes, hypertension, and dyslipidemia, assessed separately for each condition using available clinical records, laboratory results, and medication changes.
At months 3, 6, 12, and 24.
Percentage of Participants With Emergency Department Visits
Time Frame: From treatment initiation through 24 months.

Percentage of participants with at least one emergency department visit during follow-up, assessed in each treatment cohort using available records.
From treatment initiation through 24 months.
Percentage of Participants With Hospital Admissions
Time Frame: From treatment initiation through 24 months.

Percentage of participants with at least one hospital admission during follow-up, excluding the index admission for sleeve gastrectomy, assessed in each treatment cohort using available records.
From treatment initiation through 24 months.
Percentage of Participants With Early Surgical Complications
Time Frame: Within 30 days after sleeve gastrectomy.

Percentage of participants in the sleeve gastrectomy cohort experiencing a complication within 30 days after surgery, including bleeding, staple-line leak, or complications requiring reoperation. Complications will be graded using the Clavien-Dindo classification when sufficient information is available.
Within 30 days after sleeve gastrectomy.
Percentage of Participants With Late Surgical Complications
Time Frame: From postoperative day 31 through 24 months.

Percentage of participants in the sleeve gastrectomy cohort experiencing complications more than 30 days after surgery, including stenosis, gastroesophageal reflux, nutritional deficiencies, or complications requiring revision surgery, as documented in available records.
From postoperative day 31 through 24 months.

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.
Yuzuncu Yil University

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.
September 15, 2026

Primary Completion (Estimated)

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 15, 2028

Study Completion (Estimated)

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.
November 15, 2028

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).
October 22, 2026

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.
October 22, 2026

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.
October 28, 2026

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.
November 6, 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.
November 3, 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.
October 1, 2026

More Information

Terms related to this study

Keywords

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.
  • GLP-BARI-VAN

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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