An interventional study of 24-Hour Clear Liquid Diet and Standard Fasting in Retained Gastric Content, Delayed Gastric Emptying and Obesity, sponsored by Portuguese Oncology Institute, Coimbra. Not yet recruiting at 1 site in Portugal. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-10.
Sponsored by Portuguese Oncology Institute, Coimbra · Not applicable, Interventional, and Prevention
GLP-1 receptor agonists delay gastric emptying and are associated with a higher rate of retained gastric content (RGC) during upper gastrointestinal endoscopy, even under standard fasting. No randomized trial has compared fasting strategies in this population. CLEAR-GLP1 is a multicentre, international, investigator-blinded randomized trial comparing a 24-hour clear liquid diet (followed by a 2-hour fast) with standard fasting (6 hours for solids, 2 hours for clear liquids) in adults on GLP-1 RA therapy undergoing elective upper endoscopy. GLP-1 RA therapy is not interrupted in either arm. The primary outcome is the rate of clinically significant RGC, defined as a GRACE stomach score of 0.
The primary objective of the study it to determine whether a 24-hour clear liquid diet protocol reduces the incidence of retained gastric content compared with a standard fasting protocol, graded endoscopically using a validated visibility scale (stomach GRACE score=0 vs. stomach GRACE scores=1, 2 or 3), in patients on GLP-1 receptor agonist therapy undergoing elective UGI endoscopy.
323 studies on the registry are indexed under Gastroparesis; 76 are open to participants now.
This study's planned enrollment of 250 is above the median of 42 across 215 interventional studies indexed under Gastroparesis.
Browse Gastroparesis studies →Portuguese Oncology Institute, Coimbra is the lead sponsor of 8 studies on the registry; 2 are open to participants now.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
24-hour clear liquid diet: exclusively clear liquids for the 24 hours preceding the upper gastrointestinal endoscopy, with a 2-hour complete fast, including for liquids
Other: 24-Hour Clear Liquid Diet
Standard pre-procedural fasting according to current recommendations: the patient keeps a standard fasting prior to the upper gastrointestinal endoscopy, with a 6-hour fast for solid food and 2-hour fast for liquids
Other: Standard Fasting
24-hour clear liquid diet prior to upper gastrointestinal endoscopy with a 2-hour complete fast, including for liquids
Standard fasting prior to upper gastrointestinal endoscopy, of 6-hours for solid foods and 2 hours for liquids
Incidence of Retained Gastric Content
Proportion of patients with clinically significant retained gastric content, defined as a GRACE (Gastroscopy RAte of Cleanliness Evaluation) stomach score of 0 (solid food precluding visualization of the underlying mucosa), compared with GRACE stomach scores of 1, 2 or 3. The GRACE stomach score ranges from 0 to 3; higher scores indicate better mucosal cleanliness.
Time frame: During the index upper gastrointestinal endoscopy (Day 0)
Procedure interruption rate due to retained gastric content and risk of aspiration
Time frame: Day 0
Peri-procedural adverse events (aspiration, SpO₂ <90%, emergent advanced airway)
Time frame: Day 0
Inadequate visualization rate (GRACE stomach 0-1 vs 2-3)
Percentage of participants with a Gastroscopy RAte of Cleanliness Evaluation (GRACE) stomach score of 0 or 1, compared with scores of 2 or 3. The GRACE stomach score ranges from 0 to 3; higher scores indicate better mucosal cleanliness.
Time frame: Day 0
Optimal visualization rate (GRACE stomach 3 vs 0-2)
Percentage of participants with a Gastroscopy RAte of Cleanliness Evaluation (GRACE) stomach score of 3, compared with scores of 0, 1 or 2. The GRACE stomach score ranges from 0 to 3; higher scores indicate better mucosal cleanliness.
Time frame: Day 0
Gastric lesion detection rate
Gastric lesion detection rate defined as the detection of any subepithelial lesion, extensive intestinal metaplasia, dysplasia, carcinoma, neuroendocrine tumour, or lymphoma.
Time frame: Up to 4 weeks
Peri-procedural hypoglycemia (capillary glucose <70 mg/dL), before and after the procedure
Time frame: Day 0
Total GRACE score
Gastroscopy RAte of Cleanliness Evaluation (GRACE) Total Score Sum of the esophagus, stomach and duodenum GRACE scores; Range 0 to 9; higher scores indicate better mucosal cleanliness.
Time frame: Day 0
GRACE esophagus score
Gastroscopy RAte of Cleanliness Evaluation (GRACE) Esophagus Score; Range 0 to 3; higher scores indicate better mucosal cleanliness.
Time frame: Day 0
GRACE stomach score
Gastroscopy RAte of Cleanliness Evaluation (GRACE) Stomach Score; Range 0 to 3; higher scores indicate better mucosal cleanliness.
Time frame: Day 0
GRACE duodenum score
Gastroscopy RAte of Cleanliness Evaluation (GRACE) Duodenum Score; Range 0 to 3; higher scores indicate better mucosal cleanliness
Time frame: Day 0
Plan to share: Yes — De-identified individual participant data underlying the results reported in the primary publication (baseline characteristics, fasting arm, GLP-1 RA type and dose, time since last dose, GRACE scores, adverse events and lesion detection) will be shared, in compliance with the General Data Protection Regulation (GDPR).
Supporting information: Study protocol, Statistical analysis plan, Informed consent form
Time frame: Beginning 9 months and ending 36 months after publication of the primary results.
Access criteria: Researchers who provide a methodologically sound proposal, approved by the principal investigator. Proposals should be directed by email. To gain access, data requestors will need to sign a data access agreement.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is not yet recruiting, as verified in Nov 2026. You cannot join it, but the record below documents what was studied.
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Portuguese Oncology Institute, Coimbra