Preoperative Oral Carbohydrate Loading and Gastrointestinal Recovery After Bariatric Surgery in Metabolic Syndrome

September 10, 2026 updated by: Tong Mu, First Affiliated Hospital of Chongqing Medical University

Preoperative Oral Carbohydrate Loading for Enhanced Gastrointestinal Recovery After Bariatric Surgery in Patients With Metabolic Syndrome

This prospective randomized controlled trial aims to evaluate the effect of preoperative oral carbohydrate loading on postoperative gastrointestinal recovery in patients with metabolic syndrome undergoing bariatric surgery. Eligible participants will be randomly assigned to either a preoperative oral carbohydrate drink group or a standard preoperative fasting group.

The primary objective of this study is to determine whether preoperative oral carbohydrate loading can facilitate early postoperative gastrointestinal recovery. Outcome measures will include the proportion of patients achieving postoperative gastrointestinal recovery, time to postoperative gastrointestinal recovery, perioperative blood glucose levels, and other postoperative recovery-related outcomes. This study aims to provide clinical evidence regarding the efficacy and safety of preoperative oral carbohydrate loading in patients with metabolic syndrome undergoing bariatric surgery.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

This prospective, randomized trial aims to evaluate the efficacy and safety of preoperative oral carbohydrate loading for postoperative gastrointestinal recovery in patients with metabolic syndrome undergoing bariatric surgery. Eligible participants will be randomly assigned in a 1:1 ratio to either the preoperative oral carbohydrate loading group or the placebo group.

Participants in both groups will follow a standardized preoperative fasting protocol, with solid food prohibited for at least 6 hours before induction of anesthesia and clear liquids discontinued 2 hours before surgery. Participants in the POC group will consume 400 mL of an oral carbohydrate-containing beverage 2 hours before surgery, whereas participants in the control group will consume an equal volume of a placebo beverage with a similar appearance and taste but containing no carbohydrates at the same time point.

The primary outcome is postoperative gastrointestinal functional recovery, assessed using the GI-3 criteria. GI-3 recovery is defined as tolerance of oral intake accompanied by recovery of lower gastrointestinal function. The study will evaluate both the proportion of participants achieving GI-3 recovery within the predefined postoperative period and the time to GI-3 recovery.

Secondary outcomes include other measures related to postoperative gastrointestinal recovery, postoperative nausea and vomiting, quality of recovery, length of hospital stay, and other postoperative recovery-related outcomes. Perioperative blood glucose levels and glycemic variability will be assessed to evaluate the metabolic safety of preoperative oral carbohydrate loading.

Safety outcomes related to preoperative oral carbohydrate intake will also be assessed. Gastric ultrasonography will be performed before induction of anesthesia to evaluate gastric volume, corrected gastric volume, gastric antral cross-sectional area, and Perlas grade. The occurrence of perioperative regurgitation or pulmonary aspiration will also be recorded.

This study aims to determine whether, compared with placebo, preoperative oral carbohydrate loading can enhance postoperative gastrointestinal recovery in patients with metabolic syndrome undergoing bariatric surgery without increasing clinically significant perioperative glycemic fluctuations or aspiration-related risks.

Study Type

Interventional

Enrollment (Estimated)

208

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 Contact

Study Locations

  • China
    • Chongqing Municipality
      • Chongqing, Chongqing Municipality, China, 400016
        • The First Affiliated Hospital of Chongqing Medical University（No. 1 Youyi Road, Yuzhong District, Chongqing 400016, China）
        • Contact:

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

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. adults aged 18-65 years;
  2. diagnosis of metabolic syndrome (≥3 of the following: elevated waist circumference, elevated triglycerides, elevated blood pressure, elevated fasting glucose, and reduced HDL-C);
  3. eligibility for bariatric surgery(body mass index ≥35 kg/m² or metabolic disease with body mass index 27.5-34.9 kg/m²), with planned Roux-en-Y gastric bypass or sleeve gastrectomy;
  4. provision of written informed consent and willingness to complete follow-up.

Exclusion Criteria:

  1. gastrointestinal motility disorders;
  2. severe cardiovascular, pulmonary, hepatic, or renal dysfunction;
  3. with inadequate glycemic control, defined as HbA1c ≥8.0% within 3 months before surgery or fasting plasma glucose >10.0 mmol/L at the preoperative assessment;
  4. malnutrition;
  5. known allergy to carbohydrate preparations;
  6. pregnancy or lactation;
  7. previous bariatric or major upper gastrointestinal surgery;
  8. chronic use of medications known to substantially affect gastrointestinal motility.

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: Triple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: POC Group
Fasted from solid foods for ≥6 hours (≥8 hours after fatty or meat-containing meals), with clear liquids permitted until 2 hours before surgery, and consumed 400 mL of a carbohydrate-containing clear liquid 2 hours before surgery.
Other: Preoperative oral carbohydrate loading
Participants in the POC group were fasted from solid foods for ≥6 hours (≥8 hours after fatty or meat-containing meals), with clear liquids permitted until 2 hours before surgery, and consumed 400 mL of a carbohydrate-containing clear liquid 2 hours before surgery. The beverage provided 12.5 g of carbohydrates per 100 mL and contained no fiber, protein, or fat.
Placebo Comparator: Control Group
Fasted from solid foods for ≥6 hours (≥8 hours after fatty or meat-containing meals), with clear liquids permitted until 2 hours before surgery, and consumed 400 mL of a non-caloric, carbohydrate-free clear liquid with a similar appearance and taste 2 hours before surgery.
Other: The placebo
Participants in the placebo group were instructed to follow the same preoperative fasting regimen and to consume 400 mL of a matching non-caloric, carbohydrate-free clear liquid 2 hours before surgery. The placebo was similar to the carbohydrate-containing beverage in appearance and taste，but contained no carbohydrates, fiber, protein, or fat.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
GI-3 recovery rate within 72 hours after surgery
Time Frame: Within 72 hours after surgery
GI-3 is a composite endpoint defined as the ability to tolerate oral intake (consumption of food and drink at three consecutive meals without significant nausea or vomiting), accompanied by flatus or defecation.
Within 72 hours after surgery

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Time to GI-3 recovery
Time Frame: From the end of surgery up to 7 days after surgery.
From the end of surgery up to 7 days after surgery.
Time to GI-2 recovery
Time Frame: From the end of surgery up to 7 days after surgery.
GI-2 is a composite endpoint defined as the ability to tolerate oral intake (consumption of food and drink at three consecutive meals without significant nausea or vomiting), accompanied by defecation
From the end of surgery up to 7 days after surgery.
Postoperative Nausea and Vomiting Score
Time Frame: Days 1 - 4 postoperatively
Postoperative nausea and vomiting were assessed using the Postoperative Nausea and Vomiting Score, ranging from 0 to 6, with higher scores indicating more severe postoperative nausea and vomiting.
Days 1 - 4 postoperatively
15-item Quality of Recovery Score
Time Frame: Days 1 - 7 and 30 postoperatively
Quality of recovery was assessed using the 15-item Quality of Recovery Score, ranging from 0 to 150, with higher scores indicating better postoperative recovery.
Days 1 - 7 and 30 postoperatively
Perioperative blood glucose levels
Time Frame: Measured before anesthesia induction, 1 hour after incision, before leaving the operating room, and 1 hour after surgery.
Measured before anesthesia induction, 1 hour after incision, before leaving the operating room, and 1 hour after surgery.
Glycemic variability
Time Frame: Calculated based on blood glucose levels measured before anesthesia induction, 1 hour after incision, before leaving the operating room, and 1 hour after surgery.
Calculated based on blood glucose levels measured before anesthesia induction, 1 hour after incision, before leaving the operating room, and 1 hour after surgery.
Time to first postoperative flatus
Time Frame: From the end of surgery up to 7 days after surgery.
From the end of surgery up to 7 days after surgery.
Time to first postoperative defecation
Time Frame: From the end of surgery up to 7 days after surgery.
From the end of surgery up to 7 days after surgery.
Total length of hospital stay (including readmissions within 30 days after surgery)
Time Frame: Within 30 days after surgery
Within 30 days after surgery

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Unplanned readmission rate within 30 days after surgery
Time Frame: Within 30 days after surgery
Within 30 days after surgery
Postoperative complications
Time Frame: Within 30 days after surgery
Classified according to the Clavien-Dindo classification criteria for complications
Within 30 days after surgery
Gastric cross-sectional area (CSA)
Time Frame: Before anaesthetic induction
Calculated using the formula (AP × CC × π)/4, where AP is the anteroposterior diameter and CC is the craniocaudal diameter.
Before anaesthetic induction
Gastric volume
Time Frame: Before anaesthetic induction
= 27.0 + 14.6 × CSA - 1.28 × age
Before anaesthetic induction
Perlas grade
Time Frame: Before anaesthetic induction
Graded according to the Perlas system: grade 0 (no content in either position), grade 1 (only a small amount of fluid visible in the right lateral decubitus position), and grade 2 (distended antrum with fluid visible in both positions).
Before anaesthetic induction
Corrected gastric volume (CGV)
Time Frame: Before anaesthetic induction
Recalculated in mL kg-¹
Before anaesthetic induction
Incidence of regurgitation or aspiration
Time Frame: From anesthesia induction to discharge from the post-anesthesia care unit.
From anesthesia induction to discharge from the post-anesthesia care unit.

Collaborators and Investigators

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

Sponsor

First Affiliated Hospital of Chongqing Medical University

Investigators

  • Study Director: Wei Ke, PhD, First Affiliated Hospital of Chongqing Medical 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 (Estimated)

September 28, 2026

Primary Completion (Estimated)

December 1, 2026

Study Completion (Estimated)

January 1, 2027

Study Registration Dates

First Submitted

September 1, 2026

First Submitted That Met QC Criteria

September 10, 2026

First Posted (Actual)

September 16, 2026

Study Record Updates

Last Update Posted (Actual)

September 16, 2026

Last Update Submitted That Met QC Criteria

September 10, 2026

Last Verified

September 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • POC-MetS-2026-01

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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