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NCT Number: NCT05404061

The Poor Responders Study

Obesity and type 2 diabetes are major causes of illness and premature death worldwide and their incidence is increasing rapidly. Bariatric surgery is considered as the "gold-standard" surgical treatment for both conditions.

However, not all patients do equally well after surgery and indeed the weight loss experienced by patients undergoing bariatric surgery can vary. As such when patients are seen after bariatric surgery in clinic they fall in one of the following two categories:

1. Good responders: this is the majority of patients who lose the expected amount of weight based on the published studies. 2. Poor responders: this is a small group of patients who either lose less than the expected amount of weight after bariatric surgery or lose the expected amounts of weight early after surgery but then regain a substantial proportion of the weight they have lost.

The so-called "poor responders" are exposed to all the risks of the operation and do not benefit from the weight loss as much as good responders.

This study would therefore like to investigate the physiological factors that distinguish poor from good responders before, and after bariatric surgery. The study team hypothesizes that compared to good responders, poor responders exhibit:

1. a smaller degree of fullness sensation after a meal, 2. a lower energy expenditure after a meal, and 3. genetic changes (single nucleotide polymorphisms) that predispose the poor responder to development of obesity.

In addition, the study team hypothesizes that poor responders exhibit:

1. lower gut hormone secretion after a meal and 2. are less sensitive to the physiological action of gut hormones compared to good responders and that this difference in gut hormone secretion and response to gut hormones prior to bariatric surgery can be helpful to predict response to bariatric surgery.

Recruiting

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Key information

Conditions

Bariatric Surgery Candidate Body Weight Diabetes Mellitus Diabetes Mellitus, Type 2 Endocrine System Diseases Glucose Metabolism Disorders Metabolic Diseases Nutrition Disorders Nutritional and Metabolic Diseases Obesity Obesity, Morbid Overnutrition Overweight Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

18 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Imperial College London

London, W120NN, United Kingdom

Location status: Recruiting

Location contact

Kleopatra Alexiadou, PhD

CONTACT

[email protected]

02033138038 ext. 38038

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Aged 18 -70 years.
  • Male or female.
  • Previous bariatric surgery for obesity and/or diabetes (studies 1 and 2).
  • ≥1 year interval after bariatric surgery (studies 1 and 2).
  • Awaiting bariatric surgery at the Imperial Weight Centre (study 3)
  • Able to give informed consent.

Exclusion criteria

  • History of any medical, psychological or other condition, or use of any medications, including over-the-counter products, which, in the opinion of the investigators, would either interfere with the study or potentially cause harm to the volunteer.
  • Without access at home to a telephone or other factor likely to interfere with ability to participate reliably in the study.
  • Pregnancy or breastfeeding.
  • Unable to maintain adequate contraception for the duration of the study and for one month afterwards.
  • History of hypersensitivity to any of the components of the subcutaneous infusions.
  • Donated blood during the preceding 3 months or intention to do so before the end of the study.
  • Any other co-morbidity that would compromise the validity of the study or the safety of the participant such as heart failure or clinically apparent cardiovascular disease.
  • Anatomical or endocrinological pathology causing poor weight loss or weight regain
  • Uncontrolled hypertension (systolic blood pressure of 160 mmHg or above and/or diastolic blood pressure of 100 mmHg or above)
  • Participation in a research study within the last two months.
  • Unable to speak English (this is relevant to answering the psychological questionnaires)

Treatment and study plan

Gut hormones

Other

Their first visit will act as an acclimatisation visit and participants will be infused subcutaneously with a triple gut hormone infusion (GLP-1, PYY and OXM). This will not only allow us to acclimatise the study volunteer to the study visits, but also allow us to test for subject tolerability of the gut hormones.

For the next two visits participants will be randomised in a single-blinded fashion to a subcutaneous infusion of either:

  • 0.9% saline,
  • GLP-1

Primary outcomes

  1. Gut hormone secretion study: Peak plasma level of gut hormones after meal ingestion

    Time frame: During one study visit (Mixed Meal Test), at least 1 year post-surgery.

    A standardized mixed-meal tolerance test. Blood samples will be taken at intervals over four hours. These will be analysed for gut hormones.

  2. Gut hormone sensitivity study: Change in Food intake following gut hormone infusion compared to placebo.

    Time frame: During three study visits (gut hormone infusion visits), at least 1 year post-surgery.

    Ad libitum meal test. A meal will be served to participants and they will be allowed 20 minutes to eat until they feel comfortably full. Food intake will be measured at the end of the meal.

  3. Prospective assessment of gut hormone response pre and post-surgery: Change in Peak plasma level of gut hormones after meal ingestion.

    Time frame: During two study visits (Mixed Meal Test), one before and one 1 year after surgery.

    A standardized mixed-meal tolerance test. Blood samples will be taken at intervals over four hours. These will be analysed for gut hormones.

Secondary outcomes

  1. Change in Resting Energy Expenditure

    Time frame: Change between two visits: before and 1 year after bariatric surgery (Prospective assessment of gut hormone response pre and post-surgery).

    Resting energy expenditure assessment via indirect calorimetry.

  2. Change in Diet Induced Thermogenesis

    Time frame: Change between two visits: before and 1 year after bariatric surgery (Prospective assessment of gut hormone response pre and post-surgery).

    Diet induced thermogenesis assessment via indirect calorimetry.

  3. Change in Genetic factors

    Time frame: Change between two visits: Before and 1 year after bariatric surgery.

    Change in genetic factors assessed by collection of plasma DNA samples.

Study contacts

Contact information is provided by the study sponsor or research team.

Kleopatra Alexiadou, PhD

CONTACT

[email protected]

+442033138038 ext. 38038

Sponsors and collaborators

Lead sponsor

Imperial College London

Other

Registry information

Official study title

Why do Some Patients Respond Better Than Others to Bariatric Surgery?

Important dates

Study start
2018
Primary completion
2027
Study completion
2027
First posted
Jun 3, 2022
Registry last updated
May 9, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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