Condition category
Nutritional, Metabolic, Endocrine
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
No longer recruiting
Publication status
Results overdue

Plain English Summary

Background and study aims
The gut microbiota (microbe population in the intestine) plays a key role in energy storage and development of obesity and type 2 diabetes (T2DM). There are no drugs to cure T2DM successfully. A type of surgery called bariatric surgery has become an alternative, with double benefits: weight loss and glycemic improvement. The aim of the study is to evaluate and compare gut microbiota changes after advanced medical therapy and after surgery and to study associations between gut microbiota changes and metabolic/hormonal changes, including T2DM remission.

Who can participate?
Either male or female patients aged 20-65 years, with a body mass index (BMI) between 30-35Kg/m2. Participants must have been diagnosed with T2DM for at least 3 months.

What does the study involve?
Patients will be randomly allocated to one of two groups: undergo surgery or receive advanced
medical therapy. Participants will be evaluated through a 12 months follow-up period, with clinical visits and laboratory tests at months 0, 1, 3, 6 and 12.

What are the possible benefits and risks of participating?
Benefits include loss of weight, glycemic improvement or T2DM resolution. Risks are those related with bariatric surgery.

Where is the study run from?
Centro Hospitalar São João, Porto, Portugal

When is the study starting and how long is it expected to run for?
The study will start on May 2014 and will continue for a period of 16 months.

Who is funding the study?
Liga dos Amigos do Serviço de Endocrinologia, Centro Hospitalar São João, Porto, Portugal

Who is the main contact?
Dr Eva Lau

Trial website

Contact information



Primary contact

Dr Eva Lau


Contact details

Rua D. João III
nº 16 1ºH 3030-329 Coimbra

Additional identifiers

EudraCT number number

Protocol/serial number

Proj. 116/13

Study information

Scientific title

Gut microbiota changes and type 2 Diabetes Mellitus resolution in mild obesity after metabolic surgery versus advanced medical therapy



Study hypothesis

In mild obese patients (BMI 30-35 Kg/m2) with type 2 diabetes, metabolic improvement after metabolic surgery is associated with gut microbiota changes.

Ethics approval

St John's Hospital Ethics Committee, Porto (Centro Hospitalar S. João); ref. 116/13

Study design

Randomized clinical trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet


Type 2 diabetes


Patients will be assigned to receive either Roux-en-Y gastric bypass (RYGB) surgery with advanced medical treatment as needed or exclusive advanced medical treatment for T2DM
1. Anti-diabetic medical therapy, including lifestyle and nutrition counseling and drug therapy, to optimize weight loss and euglycemic control
2. RYGB surgery

Intervention type



Not Applicable

Drug names

Primary outcome measure

Assess gut microbiota changes in mild obese (BMI 30-35 Kg/m2) diabetic patients after metabolic surgery and compare the gut microbiota with mild obese (BMI 30-35 Kg/m2) diabetic patients who underwent only advanced medical therapy

Secondary outcome measures

1. Determine the rate of biochemical remission of diabetes after metabolic surgery
2. Assess changes in metabolic, hormonal and inflammatory parameters after metabolic surgery versus advanced medical therapy
3. Study influence of patient characteristics in gut microbiota changes, as well as in metabolic, hormonal and inflammatory parameters, after metabolic surgery versus advanced medical therapy
4. Study associations between type 2 diabetes remission/improvement (metabolic, hormonal and inflammatory changes) and gut microbiota composition/adaptation after metabolic surgery versus advanced medical therapy

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Age between 20-65 years old
2. BMI between 30-35Kg/m2
3. Previous diagnosis of type 2 diabetes, according to the American Diabetes Association (ADA) definition, under medical therapy
4. Duration of diabetes more than 3 months
5. Overnight-fasting C-peptide more than 0.7 ng/ml
6. Negative anti-GAD autoantibody
7. Candidate for general anesthesia
8. The ability and willingness to participate in the study, including understanding the requirements of each arm of the study (written informed consent)

Participant type


Age group




Target number of participants

A sample size of 20 participants was estimated and 10 participants were randomized by each group.

Participant exclusion criteria

1. Specific contraindication to obesity surgery
2. Diabetes secondary to a specific disease (maturity-onset diabetes of the young, latent autoimmune diabetes in adult and pancreatitis)
3. Received any antibiotic, probiotic, or prebiotic agents in the month before randomization
4. Pregnancy
5. Debilitating disease
6. Psychological conditions which may hamper patient’s cooperation
7. Any condition which, in the judgement of the investigator, may make the participation in the study risky or bias the results

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Rua D. João III, nº 16 1ºH 3030-329 Coimbra

Sponsor information


St. John's Hospital (Portugal)

Sponsor details

Alameda Prof. Hernâni Monteiro

Sponsor type

Hospital/treatment centre



Funder type

Hospital/treatment centre

Funder name

St John's Hospital, Porto (Portugal) (Associação dos Amigos do Serviço de Endocrinologia do Hospital de S. João)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes

12/08/2020: No publications found.