Weight Loss-Independent Metabolic Effects of Roux-En-Y Gastric Bypass in Diabetes (RBD-T2D)

July 17, 2025 updated by: Washington University School of Medicine
For this purpose, we will compare the effects of targeted 16-18% (with a range of 16-25%) weight loss induced by Roux-en-Y Gastric bypass (RYGB) surgery with the same weight loss induced by a low-calorie diet (LCD) on liver and skeletal muscle insulin sensitivity, beta-cell function, and 24-hour metabolic homeostasis in obese subjects with or without T2D.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

65

Phase

  • 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 Locations

  • United States
    • Missouri
      • St. Louis, Missouri, United States, 63110
        • Washington University School of Medicine

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

Ages Eligible for Study

25 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

For RYGB group:

  • Scheduled for this bariatric surgery
  • Body Mass Index (BMI) 34-55 kg/m²
  • Type 2 Diabetes
  • Signed informed consent

For Low-Calorie Diet group:

  • BMI 34-55 kg/m²
  • Type 2 Diabetes and Non-Diabetics
  • Signed informed consent

Exclusion Criteria:

For both RYGB & Low-Calorie Diet groups

  • Regular use of tobacco products
  • Previous intestinal resection
  • Pregnant or breastfeeding
  • Evidence of significant organ system dysfunction or disease other than T2D
  • Use of any medication that might, in the opinion of the investigator, affect metabolic function
  • Exercise ≥90 minutes per week

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: Basic Science
  • Allocation: Non-Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Roux-en-Y gastric bypass (RYGB)
Subjects in this group are scheduled to undergo roux-en-Y gastric bypass surgery to obtain approximately 16-18% (with a range of 16-25%) weight loss.
Procedure: Roux-en-Y gastric bypass surgery
A surgical procedure to help subjects lose approximately 16-18% (with a range of 16-25%) of their body weight.
Active Comparator: Low-calorie diet
Subjects in this group will participate in a low-calorie diet intervention to obtain approximately 16-18% (with a range of 16-25%) weight loss.
Behavioral: Low-calorie diet
Subjects will meet with a dietitian and/or behaviorist over approximately 6 months to lose approximately 16-18% (with a range of 16-25%) of their body weight.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Changes in hepatic insulin sensitivity
Time Frame: 6 months (before and after targeted weight loss)
The outcome will be assessed by hyperinsulinemic-euglycemic-pancreatic-clamp procedure before and after weight loss.
6 months (before and after targeted weight loss)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Changes in skeletal muscle and adipose tissue insulin sensitivity
Time Frame: 6 months (before and after targeted weight loss)
The outcome will be assessed by hyperinsulinemic-euglycemic-pancreatic-clamp procedure before and after weight loss.
6 months (before and after targeted weight loss)
Changes in Beta-cell function
Time Frame: 6 months (before and after targeted weight loss)
The outcome will be assessed as the product of beta-cell glucose sensitivity (ratio of post-meal insulin secretion rate to post-meal plasma glucose) during mixed-meal test and whole-body insulin sensitivity before and after weight loss.
6 months (before and after targeted weight loss)
Changes in glucose kinetics (glucose concentration and rate of appearance into the systemic circulation) in response to mixed-meal ingestion
Time Frame: 6 months (before and after targeted weight loss)
The outcome will be measured by using dual glucose tracer mixed meal metabolic test and serial blood sampling for 4 hours before and after weight loss
6 months (before and after targeted weight loss)
Changes in 24-hour plasma glucose profile
Time Frame: 6 months (before and after targeted weight loss)
The outcome will be determined by obtaining serial plasma glucose concentration measurements for 24 hours before and after weight loss
6 months (before and after targeted weight loss)
Changes in 24-hour plasma insulin profile
Time Frame: 6 months (before and after targeted weight loss)
The outcome will determined by obtaining serial plasma insulin concentration measurements for 24 hours before and after weight loss
6 months (before and after targeted weight loss)
Changes in 24-hour plasma free fatty acid profile
Time Frame: 6 months (before and after targeted weight loss)
The outcome will determined by obtaining serial plasma free fatty acid concentration measurements for 24 hours before and after weight loss
6 months (before and after targeted weight loss)
Changes in body fat mass
Time Frame: 6 months (before and after targeted weight loss)
The outcome will be measured by using dual-energy X-ray absorptiometry before and after weight loss
6 months (before and after targeted weight loss)
Changes in intra-abdominal adipose tissue volume
Time Frame: 6 months (before and after targeted weight loss)
The outcome will be measured by using magnetic resonance imaging before and after weight loss
6 months (before and after targeted weight loss)
Changes in intrahepatic triglyceride content
Time Frame: 6 months (before and after targeted weight loss)
The outcome will be measured by using magnetic resonance imaging before and after weight loss
6 months (before and after targeted weight loss)
Changes in fat free mass
Time Frame: 6 months (before and after targeted weight loss)
The outcome will be measured by using dual-energy X-ray absorptiometry before and after weight loss
6 months (before and after targeted weight loss)

Collaborators and Investigators

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

Sponsor

Washington University School of Medicine

Collaborators

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Investigators

  • Principal Investigator: Samuel Klein, MD, Washington University School of Medicine

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

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)

August 1, 2014

Primary Completion (Actual)

March 1, 2019

Study Completion (Actual)

March 1, 2019

Study Registration Dates

First Submitted

July 31, 2014

First Submitted That Met QC Criteria

July 31, 2014

First Posted (Estimated)

August 4, 2014

Study Record Updates

Last Update Posted (Actual)

July 20, 2025

Last Update Submitted That Met QC Criteria

July 17, 2025

Last Verified

July 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 201403065
  • 1R01DK101578 (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

No

product manufactured in and exported from the U.S.

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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