Insulin ResistanceMRNCT05251207
Plasma Trimethylamine N-oxide Elevation Induced by L-carnitine Supplementation and Insulin Resistance
A study testing L-carnitine, L-leucine and Change of the circadian cycle in people with Insulin Resistance, run by Poznan University of Physical Education at 1 site in Poland.
Trial summary
The primary aims of the current study: using L-carnitine supplementation modulate the level of plasma trimethylamine N-oxide to assess its effect on circulating cytokines related to diabetes and metabolic syndrome; using simulated night-shift work intervention as a stress factor, explore the effect of circulating… Read more about this study
- Who is it for?
- Ages 20 to 30 yearsHealthy volunteers can take part
- Conditions the study is for
- Insulin Resistance
- What is being tested?
- L-carnitine, L-leucine and Change of the circadian cycle
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 40 participants
- Where
- 1 sitePoland
- Study dates
- 7 Feb 2022to 13 Aug 2026
- Phase
- Interventional
- Are there results?
- None posted in the registry
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 20 to 30 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- healthy volunteers,
- must be able to swallow tablets
Who cannot join
- smokers,
- cardiovascular disease
- liver disease
- kidney disease
- gastrointestinal disorders (including stomach ulcers and erosions)
- diabetes
Trial locations and contacts
1 site in 1 country.
About this study
Official title: The Role of Gut Microbiota Metabolite, Trimethylamine N-oxide, in the Insulin Resistance Development
The primary aims of the current study:
- using L-carnitine supplementation modulate the level of plasma trimethylamine N-oxide to assess its effect on circulating cytokines related to diabetes and metabolic syndrome;
- using simulated night-shift work intervention as a stress factor, explore the effect of circulating metabolites on insulin sensitivity
The secondary aim is to evaluate the effect of carnitine supplementation on gut microbiome composition.
Read the detailed description
Subjects will be randomly divided in two groups: supplemented by L-carnitine 2g/day for 12 weeks, and placebo group receiving leucine in identical gelatine capsules.
Subjects who successfully complete the protocol will be divided into four subgroups - two with a changed circadian cycle and two controls (supplemented and placebo). Subgroups with a changed daily cycle will be able to sleep between 8:00 and 17:00 for four consecutive days, while during the night they will stay active in the laboratory. The oral glucose tolerance test (OGTT) will be performed before and after the circadian cycle modification. Glucose levels will be monitored by FreeStyle Libre Sensor. Moreover, the activity of the participants will be monitored by wearable activity trackers.
Before supplementation, as well as before circadian cycle modification and after finishing the whole experimental procedure, fasting blood samples will be collected for determination of plasma trimethylamine N-oxide (TMAO), trimethylamine (TMA), carnitine (free and acyl derivatives), protein markers of diabetes and inflammation.
Moreover, the stool samples will be collected before and after 12 weeks of supplementation, to determine the composition of the gut microbiome. In addition diet of participants will be monitored.
- Conditions
- Insulin Resistance
- Being tested
- L-carnitine, L-leucine, Change of the circadian cycle
- Medical subject headings
- Insulin Resistance
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
L-carnitineDietary supplement
L-carnitine-L-tartrate
L-leucineDietary supplement
L-leucine
Change of the circadian cycleBehavioural
Reducing sleep at night for four consecutive days (enabling sleep between 8:00 and 17:00)
| Study group | Role | What they receive |
|---|---|---|
| carnitine | Experimental | 2 grams of L-carnitine per day for 12 weeks Receives: Dietary Supplement: L-carnitine; Behavioral: Change of the circadian cycle |
| leucine | Placebo comparator | 2 grams of L-leucine per day for 12 weeks Receives: Dietary Supplement: L-leucine; Behavioral: Change of the circadian cycle |
| modified circadian cycle | Experimental | no sleep at night for four consecutive days (enabling sleep between 8:00 and 17:00). Receives: Dietary Supplement: L-carnitine; Dietary Supplement: L-leucine |
| normal circadian cycle | Active comparator | sleep at night for four consecutive days Receives: Dietary Supplement: L-carnitine; Dietary Supplement: L-leucine |
What is being measured
The primary outcome is the main question the study is designed to answer.
Circulating microbiome metabolites
Determination of plasma trimethylamine and trimethylamine N-oxide using ultra performance liquid chromatography - tandem mass spectrometer (UPLC-MS/MS) method
Measured: 13 weeks
Circulating carnitine metabolites
Determination of plasma free, total, and acyl-L-carnitines using ultra performance liquid chromatography - tandem mass spectrometer (UPLC-MS/MS) method
Measured: 13 weeks
Circulating diabetes biomarkers
insulin, C-peptide, ghrelin, leptin, resistin using enzyme-linked immunosorbent assay
Measured: 13 weeks
Circulating inflammatory biomarkers
tumor necrosis factor, C-reactive protein using enzyme-linked immunosorbent assay
Measured: 13 weeks
Oral Glucose Tolerance Test
The subjects will consume 75 g of glucose solution drink within a 5-minute time frame. The glucose level will be continuously monitored with the FreeStyle Libre Sensor.
Measured: 1 week
Secondary outcomes (1)
gut microbiome composition
16 S rRNA sequencing will be used to analyze the gut microbiome in the stool samples
Measured: 13 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 Feb 2022
- Study start7 Feb 2022
- Primary completion31 May 2026
- Study completion13 Aug 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for Insulin ResistanceStudies 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
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 40 participants (actual)
Sponsor and investigators
- Lead sponsor
- Poznan University of Physical Education
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Robert Olek, Poznan University of Physical Education
- Investigators
- Robert Olek, PhD, Principal investigator, Poznan University of Physical Education
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05251207
- Sponsor's protocol ID
- 2020/39/O/NZ7/01790
- Acronym
- MR
- Status last verified
- Aug 2026
- First submitted
- 11 Feb 2022
- Last updated
- 17 Aug 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Publications
Samulak JJ, Sawicka AK, Hartmane D, Grinberga S, Pugovics O, Lysiak-Szydlowska W, Olek RA. L-Carnitine Supplementation Increases Trimethylamine-N-Oxide but not Markers of Atherosclerosis in Healthy Aged Women. Ann Nutr Metab. 2019;74(1):11-17. doi: 10.1159/000495037. Epub 2018 Nov 28.
PubMed 30485835Bescos R, Boden MJ, Jackson ML, Trewin AJ, Marin EC, Levinger I, Garnham A, Hiam DS, Falcao-Tebas F, Conte F, Owens JA, Kennaway DJ, McConell GK. Four days of simulated shift work reduces insulin sensitivity in humans. Acta Physiol (Oxf). 2018 Jun;223(2):e13039. doi: 10.1111/apha.13039. Epub 2018 Feb 12.
PubMed 29356345
Study at a glance
From the registry record, last updated by the sponsor on 17 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Role of Gut Microbiota Metabolite, Trimethylamine N-oxide, in the Insulin Resistance Development
- ClinicalTrials.gov ID
- NCT05251207
- Acronym / sponsor ID
- MR / 2020/39/O/NZ7/01790
- Conditions
- Insulin Resistance
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 40 participants (actual)
- Lead sponsor
- Poznan University of Physical EducationUniversity, hospital or other
- Study start
- 7 Feb 2022 (actual)
- Primary completion
- 31 May 2026 (actual)
- Study completion
- 13 Aug 2026 (actual)
- First posted
- 22 Feb 2022 (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 primary aims of the current study:
- using L-carnitine supplementation modulate the level of plasma trimethylamine N-oxide to assess its effect on circulating cytokines related to diabetes and metabolic syndrome;
- using simulated night-shift work intervention as a stress factor, explore the effect of circulating metabolites on insulin sensitivity
The secondary aim is to evaluate the effect of carnitine supplementation on gut microbiome composition.
Detailed description
Subjects will be randomly divided in two groups: supplemented by L-carnitine 2g/day for 12 weeks, and placebo group receiving leucine in identical gelatine capsules.
Subjects who successfully complete the protocol will be divided into four subgroups - two with a changed circadian cycle and two controls (supplemented and placebo). Subgroups with a changed daily cycle will be able to sleep between 8:00 and 17:00 for four consecutive days, while during the night they will stay active in the laboratory. The oral glucose tolerance test (OGTT) will be performed before and after the circadian cycle modification. Glucose levels will be monitored by FreeStyle Libre Sensor. Moreover, the activity of the participants will be monitored by wearable activity trackers.
Before supplementation, as well as before circadian cycle modification and after finishing the whole experimental procedure, fasting blood samples will be collected for determination of plasma trimethylamine N-oxide (TMAO), trimethylamine (TMA), carnitine (free and acyl derivatives), protein markers of diabetes and inflammation.
Moreover, the stool samples will be collected before and after 12 weeks of supplementation, to determine the composition of the gut microbiome. In addition diet of participants will be monitored.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, investigator)
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| carnitine | Experimental | Dietary Supplement: L-carnitine, Behavioral: Change of the circadian cycle2 grams of L-carnitine per day for 12 weeks |
| leucine | Placebo comparator | Dietary Supplement: L-leucine, Behavioral: Change of the circadian cycle2 grams of L-leucine per day for 12 weeks |
| modified circadian cycle | Experimental | Dietary Supplement: L-carnitine, Dietary Supplement: L-leucineno sleep at night for four consecutive days (enabling sleep between 8:00 and 17:00). |
| normal circadian cycle | Active comparator | Dietary Supplement: L-carnitine, Dietary Supplement: L-leucinesleep at night for four consecutive days |
Who may qualify
- Ages
- 20 to 30 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (2 listed)
- healthy volunteers,
- must be able to swallow tablets
Key exclusion criteria (6 listed)
- smokers,
- cardiovascular disease
- liver disease
- kidney disease
- gastrointestinal disorders (including stomach ulcers and erosions)
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 |
|---|---|---|
| L-carnitineL-carnitine-L-tartrate | Dietary supplement | carnitine, modified circadian cycle, normal circadian cycle |
| L-leucineL-leucine | Dietary supplement | leucine, modified circadian cycle, normal circadian cycle |
| Change of the circadian cycleReducing sleep at night for four consecutive days (enabling sleep between 8:00 and 17:00) | Behavioural | carnitine, leucine |
Primary outcome
Circulating microbiome metabolites
Time frame: 13 weeks
Determination of plasma trimethylamine and trimethylamine N-oxide using ultra performance liquid chromatography - tandem mass spectrometer (UPLC-MS/MS) method
Circulating carnitine metabolites
Time frame: 13 weeks
Determination of plasma free, total, and acyl-L-carnitines using ultra performance liquid chromatography - tandem mass spectrometer (UPLC-MS/MS) method
Circulating diabetes biomarkers
Time frame: 13 weeks
insulin, C-peptide, ghrelin, leptin, resistin using enzyme-linked immunosorbent assay
Circulating inflammatory biomarkers
Time frame: 13 weeks
tumor necrosis factor, C-reactive protein using enzyme-linked immunosorbent assay
Oral Glucose Tolerance Test
Time frame: 1 week
The subjects will consume 75 g of glucose solution drink within a 5-minute time frame. The glucose level will be continuously monitored with the FreeStyle Libre Sensor.
1 secondary outcome
gut microbiome composition
Time frame: 13 weeks
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 17 Aug 2026.
- Background: PubMed 30485835Samulak JJ, Sawicka AK, Hartmane D, Grinberga S, Pugovics O, Lysiak-Szydlowska W, Olek RA. L-Carnitine Supplementation Increases Trimethylamine-N-Oxide but not Markers of Atherosclerosis in Healthy Aged Women. Ann Nutr Metab. 2019;74(1):11-17. doi: 10.1159/000495037. Epub 2018 Nov 28.
- Background: PubMed 29356345Bescos R, Boden MJ, Jackson ML, Trewin AJ, Marin EC, Levinger I, Garnham A, Hiam DS, Falcao-Tebas F, Conte F, Owens JA, Kennaway DJ, McConell GK. Four days of simulated shift work reduces insulin sensitivity in humans. Acta Physiol (Oxf). 2018 Jun;223(2):e13039. doi: 10.1111/apha.13039. Epub 2018 Feb 12.
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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. This study is not recruiting at the moment.
Robert Olek, PhD principal investigator
Poznan University of Physical Education
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing L-carnitine, L-leucine and Change of the circadian cycle in people with Insulin Resistance, run by Poznan University of Physical Education 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 2 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: finished, as of the sponsor's last update on 17 Aug 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. Some participants in this study may receive a placebo. 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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Circulating microbiome metabolites (time frame: 13 weeks). The study lists 5 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05251207, which also lists 2 linked publications.
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 17 Aug 2026.