Plain English Summary
Background and study aims
Obesity is the main cause of the world wide epidemic of diabetes. Weight loss, or bariatric, surgery produces major and sustained weight loss and is being increasingly used to treat obese diabetic patients. There was initial optimism that these procedures might cure all diabetes. However, the gold-standard operation, standard gastric bypass, effectively cures diabetes in only 4 out of 10 patients. To design a safer and more successful procedure we need to understand how bariatric surgery works to improve diabetes. Hormones from the gut are released when we eat food. They control how the body uses the food it absorbs. For example they release the sugar lowering hormone insulin, and also greatly reduce appetite, which is why one feels less hungry after eating a meal. We have discovered that the good effects of bariatric surgery, and in particular the gastric bypass, are mainly due to increased release of gut hormones, reducing patients appetite and improving the release of insulin. In this project we will be testing a new procedure called the long-limb gastric bypass. It is designed particularly to be better at helping the diabetes in overweight patients, while being as safe as the currently available standard gastric bypass. We now want to show that this new procedure works better than the standard gastric bypass by causing an even bigger increase in the release of gut hormones and therefore insulin.
Who can participate?
Obese adults (aged 18-70) with type 2 diabetes.
What does the study involve?
Participants are randomly assigned into one of two groups. Those in group 1 have a standard-limb gastric bypass. Those in group 2 have a long-limb gastric bypass. Using a newly developed technique (mass spectroscopy) we then measure the differences in gut hormone secretion between the new long-limb and the standard gastric bypass. We also use a well-tested insulin sensitivity procedure (glucose clamp), both to confirm and to investigate how and why each participants diabetes has improved after the surgery.
What are the possible benefits and risks of participating?
The measurements we will be making are non-invasive and safe. The only discomfort comes from inserting a cannula to take blood samples.
Where is the study run from?
Imperial College London, Hammersmith Hospital (lead centre) and King’s College London (UK)
When is the study starting and how long is it expected to run for?
August 2015 to February 2018
Who is funding the study?
National Institute for Health Research (UK)
Who is the main contact?
Dr Alex Miras
Dr Alex Miras
Du Cane Road
Are gut hormone changes the reason why the long-limb gastric bypass is more effective than the standard limb gastric bypass in improving type 2 diabetes mellitus? A randomised controlled trial
The aim of this study is to show that a new bariatric surgery, the long-limb gastric bypass, is more effective at treating diabetes in people with obesity than the standard-limb gastric bypass.
West London & GTAC, 29/06/2015, ref: 15/LO/0813
Randomised; Double blind; Interventional; Design type: Treatment
Primary study design
Secondary study design
Randomised controlled trial
Patient information sheet
Not available in web format, please use contact details to request a participant information sheet
Topic: Diabetes; Subtopic: Type 2; Disease: Diabetic Control, Obesity
Bariatric surgery, either the standard-limb or long-limb gastric bypass
Study Entry : Registration and one or more randomisations
Primary outcome measures
Primary outcomes as of 10/01/2017:
Mechanistic primary outcome: Peak plasma GLP-1 level as measured by laboratory assays at baseline and at the point of 20% weight loss.
Clinical primary outcome: Glycated haemoglobin (HbA1c) as measured by laboratory assays at baseline and 1 year.
Original primary outcome:
Change in peak GLP-1 level; Timepoint(s): After the mixed meal tolerance test.
Secondary outcome measures
1. Plasma levels of glucose, insulin, c-peptide, gut hormones, bile acids, FGF-19 and 21 after the mixed meal tolerance test are measured using laboratory assays at baseline, within 2 weeks and at the point of 20% weight loss
2. Rate of glucose appearance (Ra) and disposal (Rd) in the euglycaemic hyperinsulinaemic clamp is measured using mass spectroscopy/metry at baseline, within 2 weeks and at the point of 20% weight loss.
3. Faecal caloric content is measured using calorimetry at baseline, 20% weight loss and at 1 year
4. 4. Blood, urine and faecal microbial diversity and metabolomics are measured using mass spectroscopy/metry at baseline, within 2 weeks and at the point of 20% weight loss.
5. Total caloric intake and macronutrient composition is measured using dietary records at baseline and at 1 year
6. HbA1c is measured using by laboratory assays at baseline and 1 year
7. Total number of medications are measured using health records at baseline and 1 year
8. Rate of patients achieving diabetes remission is measured using HbA1c and number of medications at 1 year
9. Body weight is measured using scales at baseline and 1 year
10. Systolic, diastolic blood pressure and pulse are measured using a sphygmomanometer at baseline and 1 year
11. Serum fasting lipids are measured using laboratory assays at baseline and 1 year
12. Medical, surgical, nutritional and psychological complications are measured using health records at 1 year
13. Adverse events are measured using health records at 1 year
Overall trial start date
Overall trial end date
Participant inclusion criteria
1. Both genders
2. Age 18-70
3. Type 2 diabetes mellitus
6. On glucose-lowering medication
Target number of participants
Planned Sample Size: 50; UK Sample Size: 50
Participant exclusion criteria
1. Contraindications to bariatric surgery
2. Type 1 diabetes
3. Pregnancy or breastfeeding
4. Recent blood donation
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Imperial College London, Hammersmith Hospital (lead centre)
Du Cane Road
Trial participating centre
King’s College London
National Institute for Health Research
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
The results of this project will be published in high quality peer-reviewed journals with a wide medical and scientific readership which will allow the detail of the trial to be scrutinized by the medical and scientific community at large. The results of the study will be presented at national and international scientific meetings. All of the applicants are experts in their field and regularly lecture to professional and lay audiences on these topics. We will also disseminate our findings via the press offices of Imperial College London and King’s College London and associated NHS Trusts. Crucially, the clinical results of the trial will be disseminated through our research teams and institutions to NHS England service providers and policymakers.
Intention to publish date
Participant level data
Available on request
Results - basic reporting