ObesityBBSSNCT04634591
The Bialystok Bariatric Surgery Study
An observational study of Obesity and Diabetes Mellitus, run by Medical University of Bialystok at 1 site in Poland.
Trial summary
The Bialystok Bariatric Surgery Study (BBSS) is a prospective observational cohort study of patients undergoing bariatric surgery at the First Clinical Department of General and Endocrine Surgery at the Medical University of Bialystok. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Obesity, Diabetes Mellitus, Metabolic Syndrome
- What is being tested?
- Bariatric surgery
- Type of treatment
- Surgery or procedure
- How many people
- 1,000 participants
- Where
- 1 sitePoland
- Study dates
- 10 Sep 2015to 31 Dec 2026
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: In Bialystok Bariatric Surgery Study (BBSS), we observe a cohort study of patients who undergo bariatric surgery in the First Clinical Department of General and Endocrine Surgery of the Medical University of Bialystok. This center performs several types of bariatric surgery including Roux-en-Y gastric bypass (RYGB), adjustable gastric banding (AGB), and sleeve gastrectomy (SG) in patients referred to the clinic by general practitioners and endocrinologists and who were qualified for the surgery according to the clinical physicians. Only patients who agreed to participate in the research project, specified in detail during written and oral patients consent, are included. Moreover, the study population consists of the group of obese patients who do not undergo the surgery and are followed-up without the surgical intervention and the non-obese control group of patients without obesity.
Who may be able to join
- BMI ≥ 40 kg/m2, or BMI ≥ 35 and at least one or more obesity-related co-morbidities such as type 2 diabetes (T2D), hypertension, sleep apnea and other respiratory disorders, non-alcoholic fatty liver disease, osteoarthritis, lipid abnormalities, gastrointestinal disorders, or heart disease.
- Inability to achieve a healthy weight loss sustained for a period of time with prior weight loss efforts
- Patient consent for participation in research project
- Willingness in participation in follow-up visits
Who cannot join
- substance abuse,
- uncontrolled psychiatric illness
- expected lack of compliance
- advanced-stage cancer
- Non-obese control group:
- BMI <30
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Poland1 site, 1 recruiting
- Recruiting
Clinical Research Centre, Medical University of Bialystok
Bialystok, Podlaskie Voivodeship, 15-276
Lukasz Szczerbinski, MD, PhD, +48 85 831 81 50, lukasz.szczerbinski@umb.edu.pl
Adam Kretowski, Prof., MD, PhD
About this study
The Bialystok Bariatric Surgery Study (BBSS) is a prospective observational cohort study of patients undergoing bariatric surgery at the First Clinical Department of General and Endocrine Surgery at the Medical University of Bialystok. The BBSS consists of a battery of baseline tests established one month prior to the surgery and repeated at one, three, six, twelve and twenty four-month follow-up clinical visits.
- Conditions
- Obesity, Diabetes Mellitus, Metabolic Syndrome, Dyslipidemias, PreDiabetes
- Being tested
- Bariatric surgery
- Keywords
- bariatric surgery, diabetes treatment, prediabetes treatment, metabolic surgery
- Medical subject headings
- Obesity, Diabetes Mellitus, Metabolic Syndrome, Dyslipidemias, Prediabetic State
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Bariatric surgeryProcedure or surgery
Also called Metabolic surgery
Bariatric surgery (Roux-en-Y gastric bypass, gastric banding, or sleeve gastrectomy) for the treatment of morbid obesity
| Study group | Role | What they receive |
|---|---|---|
| Obesity - undergoing bariatric surgery | Patients with morbid obesity, treated with the bariatric surgery Receives: Procedure: Bariatric surgery | |
| Obesity - without bariatric surgery treatment | Patients with morbid obesity, not treated with the bariatric surgery | |
| Non-obese | Non-obese patients - control group (without obesity and without the bariatric surgery treatment) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Weight loss
Changes in total body weight under the surgery
Measured: 1, 3, 6, 12 and 24 months after the surgery
Lean body mass
Changes in total lean body mass under the surgery, measured using the whole-body dual-energy X-ray absorptiometry (DXA)
Measured: 1, 3, 6, 12 and 24 months after the surgery
Fat mass
Changes in total fat mass under the surgery, measured using the whole-body dual-energy X-ray absorptiometry (DXA)
Measured: 1, 3, 6, 12 and 24 months after the surgery
Visceral adipose tissue mass
Changes in visceral adipose tissue mass under the surgery, measured using the whole-body dual-energy X-ray absorptiometry (DXA)
Measured: 1, 3, 6, 12 and 24 months after the surgery
Fasting glucose
Changes in fasting glucose concentration under the surgery, measured in plasma using the colorimetric method
Measured: 1, 3, 6, 12 and 24 months after the surgery
Triglycerides (TG)
Changes in serum triglycerides concentration under the surgery, measured using the colorimetric method
Measured: 1, 3, 6, 12 and 24 months after the surgery
High-density lipoprotein cholesterol (HDL)
Changes in serum High-density lipoprotein cholesterol (HDL) concentration under the surgery, measured using the colorimetric method
Measured: 1, 3, 6, 12 and 24 months after the surgery
Low-density lipoprotein cholesterol (LDL)
Changes in serum Low-density lipoprotein cholesterol (LDL) concentration under the surgery, measured using the colorimetric method
Measured: 1, 3, 6, 12 and 24 months after the surgery
Total cholesterol
Changes in serum total cholesterol concentration under the surgery, measured using the colorimetric method
Measured: 1, 3, 6, 12 and 24 months after the surgery
Fasting insulin
Changes in fasting insulin concentration under the surgery, measured by the immunoradiometric assay (IRMA)
Measured: 1, 3, 6, 12 and 24 months after the surgery
2-hour glucose
Changes in glucose concentration at 2-hour of the oral glucose tolerance test under the surgery, measured in plasma using the colorimetric method
Measured: 1, 3, 6, 12 and 24 months after the surgery
Haemoglobin A1c (HbA1c)
Changes in Haemoglobin A1c under the surgery, measured by the high-performance liquid chromatography (HPLC) method
Measured: 1, 3, 6, 12 and 24 months after the surgery
Homeostatic model assessment for insulin resistance (HOMA-IR)
Changes in Homeostatic model assessment for insulin resistance under the surgery
Measured: 1, 3, 6, 12 and 24 months after the surgery
Homeostatic model assessment of beta cell function (HOMA-beta)
Changes in Homeostatic model assessment of beta cell function under the surgery
Measured: 1, 3, 6, 12 and 24 months after the surgery
Changes in glucose and insulin concentrations during the oral glucose tolerance test (OGTT)
Changes in concentrations of glucose and insulin during the oral glucose tolerance test, under the surgery
Measured: 1, 3, 6, 12 and 24 months after the surgery
Changes in glucose and insulin concentrations during the mixed meal tolerance test (MMTT)
Changes in concentrations of glucose and insulin during the mixed meal tolerance test, under the surgery
Measured: 1, 3, 6, 12 and 24 months after the surgery
Changes in GI hormones concentrations during the oral glucose tolerance test (OGTT)
Changes in concentrations of gastrointestinal hormones during the oral glucose tolerance test, under the surgery
Measured: 1, 3, 6, 12 and 24 months after the surgery
Changes in GI hormones concentrations during the mixed meal tolerance test (MMTT)
Changes in concentrations of gastrointestinal hormones during the mixed meal tolerance test, under the surgery
Measured: 1, 3, 6, 12 and 24 months after the surgery
Secondary outcomes (10)
Plasma metabolome
Changes in plasma metabolites concentrations measured using untargeted metabolomics, in response to the surgery
Measured: 1, 3, 6, 12 and 24 months after the surgery
Plasma proteome
Changes in plasma proteins concentrations measured using targeted and untargeted proteomics, in response to the surgery
Measured: 1, 3, 6, 12 and 24 months after the surgery
Urine metabolome
Changes in urine metabolites concentrations measured using untargeted metabolomics, in response to the surgery
Measured: 1, 3, 6, 12 and 24 months after the surgery
Skeletal muscle transcriptome
Changes in skeletal muscle gene and small RNA expressions measured using untargeted transcriptomics, in response to the surgery
Measured: 1, 3, 6, 12 and 24 months after the surgery
Liver transcriptome
Changes in liver gene and small RNA expressions measured using untargeted transcriptomics, in response to the surgery
Measured: 1, 3, 6, 12 and 24 months after the surgery
Adipose tissue transcriptome
Changes in adipose tissue gene and small RNA expressions measured using untargeted transcriptomics, in response to the surgery
Measured: 1, 3, 6, 12 and 24 months after the surgery
Circulating microRNA
Changes in circulating microRNAs expression, in response to the surgery
Measured: 1, 3, 6, 12 and 24 months after the surgery
Liver methylome
Changes in liver DNA methylations measured using Reduced representation bisulfite sequencing (RRBS) method, in response to the surgery
Measured: 1, 3, 6, 12 and 24 months after the surgery
Skeletal muscle methylome
Changes in skeletal muscle DNA methylations measured using Reduced representation bisulfite sequencing (RRBS) method, in response to the surgery
Measured: 1, 3, 6, 12 and 24 months after the surgery
Adipose tissue methylome
Changes in adipose tissue DNA methylations measured using Reduced representation bisulfite sequencing (RRBS) method, in response to the surgery
Measured: 1, 3, 6, 12 and 24 months after the surgery
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 Nov 2020
- Study start10 Sep 2015
- Primary completion31 Dec 2026 (estimated)
- Study completion31 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for ObesityStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case-control
- Time perspective
- Prospective
- Enrolment
- 1,000 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Medical University of Bialystok
- Sponsor type
- University, hospital or other
- Collaborators
- University of Copenhagen
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04634591
- Sponsor's protocol ID
- R-I-002/546/2015
- Acronym
- BBSS
- Status last verified
- May 2025
- First submitted
- 12 Nov 2020
- Last updated
- 14 Apr 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 14 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Bialystok Bariatric Surgery Study
- ClinicalTrials.gov ID
- NCT04634591
- Acronym / sponsor ID
- BBSS / R-I-002/546/2015
- Conditions
- Obesity, Diabetes Mellitus, Metabolic Syndrome, Dyslipidemias, PreDiabetes
- Keywords
- bariatric surgery, diabetes treatment, prediabetes treatment, metabolic surgery
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 1,000 participants (estimated)
- Lead sponsor
- Medical University of BialystokUniversity, hospital or other
- Collaborators
- University of Copenhagen
- Study start
- 10 Sep 2015 (actual)
- Primary completion
- 31 Dec 2026 (estimated)
- Study completion
- 31 Dec 2026 (estimated)
- First posted
- 18 Nov 2020 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The Bialystok Bariatric Surgery Study (BBSS) is a prospective observational cohort study of patients undergoing bariatric surgery at the First Clinical Department of General and Endocrine Surgery at the Medical University of Bialystok. The BBSS consists of a battery of baseline tests established one month prior to the surgery and repeated at one, three, six, twelve and twenty four-month follow-up clinical visits.
Study design
- Observational model
- Case-control
- Time perspective
- Prospective
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Obesity - undergoing bariatric surgery | – | Procedure: Bariatric surgeryPatients with morbid obesity, treated with the bariatric surgery |
| Obesity - without bariatric surgery treatment | – | –Patients with morbid obesity, not treated with the bariatric surgery |
| Non-obese | – | –Non-obese patients - control group (without obesity and without the bariatric surgery treatment) |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- In Bialystok Bariatric Surgery Study (BBSS), we observe a cohort study of patients who undergo bariatric surgery in the First Clinical Department of General and Endocrine Surgery of the Medical University of Bialystok. This center performs several types of bariatric surgery including Roux-en-Y gastric bypass (RYGB), adjustable gastric banding (AGB), and sleeve gastrectomy (SG) in patients referred to the clinic by general practitioners and endocrinologists and who were qualified for the surgery according to the clinical physicians. Only patients who agreed to participate in the research project, specified in detail during written and oral patients consent, are included. Moreover, the study population consists of the group of obese patients who do not undergo the surgery and are followed-up without the surgical intervention and the non-obese control group of patients without obesity.
Key inclusion criteria (4 listed)
- BMI ≥ 40 kg/m2, or BMI ≥ 35 and at least one or more obesity-related co-morbidities such as type 2 diabetes (T2D), hypertension, sleep apnea and other respiratory disorders, non-alcoholic fatty liver disease, osteoarthritis, lipid abnormalities, gastrointestinal disorders, or heart disease.
- Inability to achieve a healthy weight loss sustained for a period of time with prior weight loss efforts
- Patient consent for participation in research project
- Willingness in participation in follow-up visits
Key exclusion criteria (6 listed)
- substance abuse,
- uncontrolled psychiatric illness
- expected lack of compliance
- advanced-stage cancer
- BMI <30
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Bariatric surgeryAlso: Metabolic surgeryBariatric surgery (Roux-en-Y gastric bypass, gastric banding, or sleeve gastrectomy) for the treatment of morbid obesity | Procedure or surgery | Obesity - undergoing bariatric surgery |
Primary outcome
Weight loss
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Changes in total body weight under the surgery
Lean body mass
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Changes in total lean body mass under the surgery, measured using the whole-body dual-energy X-ray absorptiometry (DXA)
Fat mass
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Changes in total fat mass under the surgery, measured using the whole-body dual-energy X-ray absorptiometry (DXA)
Visceral adipose tissue mass
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Changes in visceral adipose tissue mass under the surgery, measured using the whole-body dual-energy X-ray absorptiometry (DXA)
Fasting glucose
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Changes in fasting glucose concentration under the surgery, measured in plasma using the colorimetric method
Triglycerides (TG)
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Changes in serum triglycerides concentration under the surgery, measured using the colorimetric method
High-density lipoprotein cholesterol (HDL)
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Changes in serum High-density lipoprotein cholesterol (HDL) concentration under the surgery, measured using the colorimetric method
Low-density lipoprotein cholesterol (LDL)
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Changes in serum Low-density lipoprotein cholesterol (LDL) concentration under the surgery, measured using the colorimetric method
Total cholesterol
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Changes in serum total cholesterol concentration under the surgery, measured using the colorimetric method
Fasting insulin
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Changes in fasting insulin concentration under the surgery, measured by the immunoradiometric assay (IRMA)
2-hour glucose
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Changes in glucose concentration at 2-hour of the oral glucose tolerance test under the surgery, measured in plasma using the colorimetric method
Haemoglobin A1c (HbA1c)
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Changes in Haemoglobin A1c under the surgery, measured by the high-performance liquid chromatography (HPLC) method
Homeostatic model assessment for insulin resistance (HOMA-IR)
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Changes in Homeostatic model assessment for insulin resistance under the surgery
Homeostatic model assessment of beta cell function (HOMA-beta)
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Changes in Homeostatic model assessment of beta cell function under the surgery
Changes in glucose and insulin concentrations during the oral glucose tolerance test (OGTT)
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Changes in concentrations of glucose and insulin during the oral glucose tolerance test, under the surgery
Changes in glucose and insulin concentrations during the mixed meal tolerance test (MMTT)
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Changes in concentrations of glucose and insulin during the mixed meal tolerance test, under the surgery
Changes in GI hormones concentrations during the oral glucose tolerance test (OGTT)
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Changes in concentrations of gastrointestinal hormones during the oral glucose tolerance test, under the surgery
Changes in GI hormones concentrations during the mixed meal tolerance test (MMTT)
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Changes in concentrations of gastrointestinal hormones during the mixed meal tolerance test, under the surgery
10 secondary outcomes
Plasma metabolome
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Plasma proteome
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Urine metabolome
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Skeletal muscle transcriptome
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Liver transcriptome
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Adipose tissue transcriptome
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Circulating microRNA
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Liver methylome
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Skeletal muscle methylome
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Adipose tissue methylome
Time frame: 1, 3, 6, 12 and 24 months after the surgery
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 14 Apr 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Clinical Research Centre, Medical University of Bialystok
Bialystok, Poland
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Obesity and Diabetes Mellitus, run by Medical University of Bialystok at 1 site in Poland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 14 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Poland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Each site lists its own contact: choose the nearest one under Trial locations. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Weight loss (time frame: 1, 3, 6, 12 and 24 months after the surgery). The study lists 18 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 14 Apr 2026.