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Active, not recruitingNCT05345106IRONmiRNAUpdated Mar 31, 2026

Inter-relationships Among Glucose, Brain, Gut Microbiota and MicroRNAs (IRONmiRNA).

An observational study in Obesity, sponsored by Institut d'Investigació Biomèdica de Girona Dr. Josep Trueta. Active, not recruiting at 1 site in Spain. Open to participants aged 30 Years to 65 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-03-31.

Sponsored by Institut d'Investigació Biomèdica de Girona Dr. Josep Trueta · Observational

Study type
Observational
Model
Case-control
Time perspective
Prospective
Enrollment
138
Ages
30 Years to 65 Years
Sex
All
01

Study summary

The brain is a recognized target of iron deposition. This process is enhanced by the presence of obesity and hyperglycemia and impacts cognitive functions. There is evidence suggesting that the gut microbiota composition modulates this process. It has been proposed that microRNAs are mediators in the dialogue between the composition and functionality of the intestinal microbiota and increased iron deposition in the brain.

The hypothesis is that circulating microRNAs are associated with parameters of cognitive dysfunction, gut microbiota, brain iron content, glucose levels, and physical activity in subjects with and without obesity.

The study includes both a cross-sectional (comparison of subjects with and without obesity) and a longitudinal design (evaluation one year after weight loss induced by bariatric surgery or by diet in patients with obesity) to evaluate the associations between circulating microRNAs, continuous glucose monitoring, brain iron content (by magnetic resonance), cognitive function (by means of cognitive tests), physical activity (measured by activity and sleep tracker device) and the composition of the microbiota, evaluated by metagenomics.

Read the detailed description

Subjects and methods:

A. Cross-sectional study:

Patients with obesity previously scheduled at the Service of Endocrinology, Diabetes, and Nutrition (UDEN) of the Hospital "Dr. Josep Trueta" of Girona (Spain) will be recruited and studied. Subjects without obesity will also be recruited through a public announcement.

A glycemia sensor will be inserted for ten days, as well as an activity and sleep tracker device (Fitbit) to record physical activity during this period of time. Interstitial subcutaneous glucose concentrations will be monitored on an outpatient basis for a period of time of 10 consecutive days using a glucose sensor validated by the Food and Drug Administration (Dexcom G6 ®). The sensor will be inserted on day 0 and it will retire on day 10 mid-morning.

Glucose records will preferably be evaluated on days 2 to 9 to avoid the bias caused by the insertion and removal of the sensor, which prevents a sufficient stabilization of the monitoring system. The characteristic glycemic pattern of each patient will be calculated on average from the profiles obtained on days 2 to 9.

At the end of the week, magnetic resonance imaging will be done to evaluate the iron content in the brain and parameters of "Diffusion Tensor Imaging" in different brain territories.

Cognitive tests will be carried out, and feces and urine will be collected for the study of the microbiota. Additionally, blood samples will be collected for the extraction and purification of circulating RNA and then retrotranscription of circulating miRNAs and preamplification.

The project will be carried out in subjects with obesity (20 men, 20 premenopausal women, and 20 women postmenopausal, Body mass index (BMI) > = 30kg/m2) and subjects without obesity, similar in age, sex, and menopausal status (20 men, 20 premenopausal women, and 20 postmenopausal women, BMI \<30kg/m2).

B. Longitudinal study:

After one year of follow-up, in which, subjects with obesity will undergo conventional treatment (hypocaloric diet, and physical activity advice) or bariatric surgery for weight loss, a second visit will be carried out.

For comparison, the same protocol of the cross-sectional study will be done again. See the information above.

DATA COLLECTION OF SUBJECTS OF CROSS-SECTIONAL AND LONGITUDINAL STUDIES:

  1. Subsidiary data: Age, sex, and birth date.

  2. Clinical variables:

    • Weight
    • height,
    • body mass index
    • waist and hip perimeters
    • waist-to-hip ratio
    • blood pressure (systolic and diastolic)
    • fat mass and fat free-mass (bioelectric impedance and DEXA)
    • smoking status
    • alcohol intake
    • registry of usual medicines
    • personal history of blood transfusion and/or donation
    • a record of family history of obesity, cardiovascular events, and diabetes
    • psychiatric and eating disorder history.

  3. Laboratory variables: 15cc of blood will be extracted from fasted subjects to determine the following variables using the usual routine techniques of the clinical laboratory:

    • hemogram
    • glucose
    • bilirubin
    • aspartate aminotransferase (AST/GOT)
    • alanine aminotransferase (ALT/GPT)
    • gamma-glutamyl transpeptidase (GGT)
    • urea
    • creatinine
    • uric acid
    • total proteins,
    • albumin
    • total cholesterol \| HDL cholesterol \| LDL cholesterol
    • triglycerides,
    • glycated hemoglobin (HbA1c)
    • ferritin \| soluble transferrin receptor
    • ultrasensitive C reactive protein
    • erythrocyte sedimentation rate
    • lipopolysaccharide binding protein
    • free thyroxine (free T4) \| thyroid stimulating hormone (TSH) \| baseline cortisol -plasma insulin
    • inflammation markers \| interleukin 6 (IL-6). An additional 15cc of blood (plasma-EDTA) will be extracted for further analyses.

  4. Stool samples collection: A stool sample will be provided from each patient. The sample should be collected at home or in the hospital, sent to the laboratory within 4 hours from the collection, fragmented, and stored at -80ºC.

    Analysis of gut microbiota in stool:

    *Determination of bacterial DNA and mRNA and study of the LBP binding protein in the blood for the detection of bacterial translocation. LBP binding protein in the blood for the detection of bacterial translocation. Hiseq and Nextseq technology (qPCR and protein analysis (WB, ELISA), OMICS (RNAseq, 16S, Metabolomics, Metagenomics).

  5. Urine sample collection: Necessary to determine alterations in the metabolic pathways involved in tryptophan metabolism, and to determine the role of the intestinal microbiota in these metabolic changes.
  6. Magnetic Resonance Imaging: All MRI examinations will be performed on a 1.5-T scanner (Ingenia ®; Philips Medical Systems). First, a fluid-attenuated inversion recovery (FLAIR) sequence will be used to exclude subjects with preexisting brain lesions. Brain iron load will be assessed by means of R2* values. T2* relaxation data will be acquired with a multi-echo gradient-echo sequence with 10 equally spaced echoes (first echo=4.6ms; inter echo spacing=4.6ms; repetition time=1300ms). T2* will be calculated by fitting the single exponential terms to the signal decay curves of the respective multi-echo data.R2* values will be calculated as R2*=1/T2* and expressed as Hz. In addition, R2* values will be converted to μmol Fe/g units as previously validated on phantom tests. Brain iron images from control subjects will be normalized to a standard space using a template image for this purpose (EPI MNI template). Subsequently, all normalized images will be averaged for the determination of normal iron content. Normal values (mean and SD) will be also calculated for anatomical regions of interest using different atlas masks, addressing possible differences between gender and age. The brain iron comparison between control and obese subjects will be performed using voxel-based analysis. Obese-subject images will be normalized to a standard space. The normalized image will be compared to the normal population using t-test analysis with age and sex as co-variables. As a result, a parametric map will show individual differences in the iron deposition. Based on previous observational studies showing increased brain iron load at some specific regions and the evidence suggesting hippocampal and hypothalamic changes in association with obesity and insulin resistance, the statistical and image analyses will be focused on iron differences at the caudate, lenticular, thalamus, hypothalamus, hippocampus, and amygdala.
  7. Neuropsychological examination: Different domains of cognition will be explored: memory (Test aprendizaje verbal-TAVEC, Rey-Osterrieth Complex Figure) attention, and executive function(WAIS-IV, Trail making test (Part A y B), Stroop test), social cognition(POFA and BFRT), language (animals). Furthermore, depression (PHQ9), anxiety (State-Trait Anxiety Inventory (STAI)), impulsivity (Impulsive Behavior Scale (UPPS-P)), sensitivity to punishment and reward (Sensitivity to Punishment and Sensitivity to Reward (SRSPQ)), food addiction (Yale Food Addiction Scale (YFAS II)), subjective well being, positive and negative affect (Positive and Negative Affect Schedule (PANAS)) will be explored through psychological tests.

  8. Profile of circulating miRNAs

    • Circulating RNA extraction and purification: Plasma will be obtained by standard venipuncture and centrifugation using EDTA-coated Vacutainer tubes (Becton-Dickinson, Franklin Lakes, NJ). Plasma separation will be performed by double centrifugation using a laboratory centrifuge (Beckman J-6M Induction Drive Centrifuge, Beckman Instruments Inc). RNA extraction will be performed from an initial volume of 300 μL of plasma using the mirVana PARIS isolation kit (Applied Biosystems, Darmstadt, Germany).
    • Retrotranscription of circulating miRNAs and preamplification: A fixed volume of 3 μL of RNA solution from the 40 mL, eluate of the RNA isolate will be used as input for retrotranscription using the TaqMan miRNA reverse transcription kit (Life Technology, Darmstadt, Germany). Preamplification will be carried out using the TaqMan PreAmp Master Mix (Life Technology, Darmstadt, Germany).
    • Analysis of individual miRNAs by TaqMan hydrolysis probes: Gene expression will be assessed by real-time PCR using the LightCycler 480 real-time PCR system (Roche Diagnostics, Barcelona, Spain), using the appropriate TaqMan technology for the quantification of relative gene expression.

The information will remain registered in a notebook and will be computerized in the database of the study.

STATICAL METHODS:

Sample size: There are no previous data showing expected differences for sample size estimation regarding glucose variability, physical activity, the composition of gut microbiota, and cognitive function. In a previous study, differences in brain iron content were observed in 20 obese vs. 20 nonobese subjects. Thus, the proposed sample size is at least 20 individuals per group, with balanced age and gender (pre-and postmenopausal women) representation.

Statistical analyses: Firstly, normal distribution and homogeneity of variances will be tested. To determine differences between study groups, it will be used χ2 for categorical variables, unpaired Student's t-test in normal quantitative, and Mann-Whitney U test for non-normal quantitative variables. Nonparametric Spearman analysis will be used to determine the correlation between quantitative variables. The same tests will also be used to study differences before and after follow-up. The significant associations, whether positive or negative, will be explored more in-depth (simple and multivariate linear regression analyses).

The microbiota composition will be analyzed and compared using R "ALDEx2". Bacterial species and functions associated with brain iron and circulating microRNAs will be identified using robust linear regression models as implemented in the R package (Limma R). Moreover, p-values will be adjusted for multiple comparisons using the R package "SGoF".Measures of glycemic variability will be calculated using Matlab software (R2018a).

02

Conditions studied

  • Obesity

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Keywords

  • Continous Glucose Monitoring
  • Cognition
  • Brain Iron content
03

In context

Obesity

6,296 studies on the registry are indexed under Obesity; 1,692 are open to participants now.

This study's enrollment of 138 is close to the median of 135 across 1,283 observational studies indexed under Obesity.

Browse Obesity studies →

Lead sponsor

Institut d'Investigació Biomèdica de Girona Dr. Josep Trueta is the lead sponsor of 29 studies on the registry; 8 are open to participants now.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
30 Years to 65 Years
Sexes eligible
All
Accepts healthy volunteers
Yes
Sampling method
Non-probability sample

Study population

Patients with obesity, without known type 2 diabetes, previously scheduled at the Service of Endocrinology, Diabetes and Nutrition (UDEN) of the Hospital "Dr. Josep Trueta" of Girona (Spain) will be recruited and studied.

Subjects without obesity will also be recruited through a public announcement.

Inclusion criteria

  1. Men and women aged 30-65 years.
  2. Informed consent for participation in the study.

Exclusion criteria

Exclusion Criteria:

  1. Serious systemic disease unrelated to obesity such as cancer, severe kidney, or liver disease, known type 1 or type 2 diabetes.
  2. Systemic diseases with intrinsic inflammatory activity such as rheumatoid arthritis, Crohn's disease, asthma, chronic infection (e.g., HIV, active tuberculosis) or any type of infectious disease.
  3. Pregnancy and lactation.
  4. Patients with severe disorders of eating behaviour.
  5. Persons whose liberty is under legal or administrative requirement.
  6. Clinical symptoms and signs of infection in the previous month.
  7. Antibiotic, antifungal or antiviral treatment in the previous 3 months.
  8. Anti-inflammatory chronic treatment with steroidal and/or non-steroidal anti-inflammatory drugs.
  9. Major psychiatric antecedents.
  10. Excessive alcohol intake, either acute or chronic (alcohol intake greater than 40 g a day (women) or 80 g/day (men)) or drugs abuse.
  11. Serum liver enzymes (AST, ALT) activity over twice the upper limit of normal.
  12. History of disturbances in iron balance (e.g., genetic hemochromatosis, hemosiderosis from any cause, atransferrinemia, paroxysmal nocturnal hemoglobinuria).
05

Study design

Observational model
Case-control
Time perspective
Prospective
Enrollment
138 participants (actual)
Patient registry
No

Groups and cohorts

  • Premenopausal women with obesity

    Procedure: Bariatric Surgery

  • Postmenopausal women with obesity

    Procedure: Bariatric Surgery

  • Men with obesity

    Procedure: Bariatric Surgery

  • Premenopausal women without obesity
  • Postmenopausal women without obesity
  • Men without obesity

Interventions

  • ProcedureBariatric Surgery

    Subjects with obesity (N=60) will be undertaken a hypocaloric diet and a periodic follow up, also 30 of them will undergo bariatric surgery

06

What researchers measure

Primary outcomes

  1. Concentration of advanced glycation end products (AGE) receptor agonists.

    Enzyme-linked immunosorbent assay (ELISA).

    Time frame: 30 months

  2. Glycemic variability.

    Mean and standard deviation of glucose measures in mg/dL using a continuous glucose monitoring during 10 days.

    Time frame: 30 months

  3. The percentage of time in glucose target range (glucose level 100mg/dl-125mg/dl)

    Time frame: 30 months

  4. The glycaemic risk measured with low blood glucose index (LBGI)

    Low blood glucose index (LBGI) is a parameter that quantifies the risk of glycaemic

    Time frame: 30 months

  5. The glycaemic risk measured with high blood glucose index (HBGI)

    High blood glucose index (HBGI) is a parameter that quantifies the risk of glycaemic

    Time frame: 30 months

  6. The glycaemic variability measured with mean amplitude of glycaemic excursions (MAGE)

    measured in mg/dl

    Time frame: 30 months

  7. Minutes light sleep

    Mean and standard deviation of minutes light sleep measures by activity and sleep tracker device.

    Time frame: 30 months

  8. Minutes deep sleep

    Mean and standard deviation of minutes deep sleep measures by activity and sleep tracker device.

    Time frame: 30 months

  9. Minutes rapid eye movement (REM)

    Mean and standard deviation of minutes REM measures by activity and sleep tracker device.

    Time frame: 30 months

Secondary outcomes

  1. Effect on brain structure.

    Brain structure will be assessed using magnetic resonance imaging.

    Time frame: 30 months

  2. Effect on gut microbiota.

    Gut microbiota will be analysed by metagenomics and metabolomics.

    Time frame: 30 months

  3. Changes from baseline in circulating concentration of AGE receptor agonists and glycemic variability one year of follow-up after weight loss in association with changes in brain structure and gut microbiota.

    Subjects with obesity will be undertaken conventional treatment or bariatric surgery for weight loss; controls will not undergo any additional measure.

    Time frame: 30 months

  4. Anxiety state

    It will be measured by State-Trate Anxiety Inventory (STAI).

    Time frame: 30 months

  5. Audioverbal memory

    It will be measured by California Verbal Learning Test (CVLT). Minimum/maximum scale values (0-16), where 16 is a better audioverbal memory.

    Time frame: 30 months

  6. Visual memory

    It will be measured by Rey-Osterrieth Complex Figure. Minimum/maximum scale values (0-36), where 36 is a better visual memory

    Time frame: 30 months

  7. Depressive symptomatology

    It will be measured by Patient Health Questionnaire-9 (PHQ-9). Minimum/maximum scale values (0-27), where ≥ 20 is severe depression.

    Time frame: 30 months

  8. Impulsivity

    It will be measured by Impulsive Behavior Scale (UPPS-P). The test evaluates: Negative

    Time frame: 30 months

  9. Food Addiction

    It will be measured by Yale Food Addiction Scale.It is a symptom score from 0-11, based on the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria, for substance dependence. Food addiction is diagnosed if ≥3 symptoms are reported.

    Time frame: 30 months

  10. Behavioral inhibition

    It will be measured by Sensitivity to Punishment and Sensitivity to Reward (SPSRQ). The scale of sensitivity to punishment is related to the behavioral inhibition system. It is made up of two subscales of 24 items each, where the higher the score, the greater the sensitivity to punishment.

    Time frame: 30 months

  11. Behavioral activation

    It will be measured by Sensitivity to Punishment and Sensitivity to Reward (SPSRQ). The reward sensitivity scale is related to the behavioral activation system. It is made up of two subscales of 24 items each, where the higher the score, the greater the sensitivity to reward.

    Time frame: 30 months

  12. Visoconstructive function

    It will be measured by Rey-Osterrieth Complex Figure. Minimum/maximum scale values (0-36), where 36 is a better visoconstructive function.

    Time frame: 30 months

  13. Selective and alternating attention

    It will be measured by Trail making test (Part A y B).

    Time frame: 30 months

  14. Attention and working memory

    It will be measured by the Digits subtest of Wechsler Adult Intelligence Scales, Fourth Edition (WAIS-IV).

    Time frame: 30 months

  15. Inhibition

    It will be measured by Stroop Color-Word Test.

    Time frame: 30 months

  16. Phonemic verbal fluency

    It will be measured by PMR.

    Time frame: 30 months

  17. Semantic verbal fluency

    It will be measured by Animals test. The person must name as many animals as possible in 1 minute. The result is corrected by standard scores, according to age and level of education.

    Time frame: 30 months

  18. Facial recognition

    It will be measured by Picture of Facial Recognition Test (POFA).

    Time frame: 30 months

  19. Emotion recognition

    It will be measured by Benton Facial Recognition Test (BFRT).This test evaluates the recognition of the five basic emotions: happiness, sadness, surprise, disgust, and anger.

    Time frame: 30 months

  20. Diffusion Tensor Imaging brain sequences

    Diffusion Tensor Imaging was acquired at 1.5 T (Philips ingenia) using a single-shot spin echo sequence with echo-planar imaging (EPI), 50 contiguous slices, voxel size 2x2x2.5 mm3, TE/TR of 72/3581 ms/ms, a diffusion-weighting factor b = 800 s/mm2 and diffusion encoding along 32 directions.

    Time frame: 30 months

  21. Brain iron accumulation

    It will be assessed using magnetic resonance imaging using (R2\*)

    Time frame: 30 months

  22. Resting-state functional brain sequences

    It will be assessed using magnetic resonance imaging (T2\*-weighted echo-planar imaging). T2 \* relaxation data will be acquired with a multi-echo gradient sequence with 10 equidistant echoes (first echo = 4.6ms; echo spacing = 4.6ms; repetition time = 1300ms). The value value of T2 \* will be calculated by adjusting the simple exponential terms for the signal decay of the respective echo time values.

    Time frame: 30 months

  23. Insulin resistance

    It will be measured by HOMA

    Time frame: 30 months

  24. Markers of chronic inflammation: C-reactive protein, IL-6, adiponectin and soluble, tumor necrosis factor-α receptor fractions.

    Enzyme-linked immunosorbent assay (ELISA) and quantitative polymerase chain reaction (qPCR)

    Time frame: 30 months

  25. Glycosylated hemoglobin (HbA1c) value

    Glycosylated hemoglobin (HbA1c) in % or mmol/mol

    Time frame: 30 months

  26. The percentage of time in hyperglycaemia (glucose level above 250 mg/dl)

    Time frame: 30 months

  27. The percentage of time in hypoglycaemia (glucose level below 70mg/dl)

    Time frame: 30 months

  28. The percentage of time in glucose range (glucose level below 100 mg/dl)

    Time frame: 30 months

  29. The percentage of time in glucose range (glucose level between 126-139 mg/dl)

    Time frame: 30 months

  30. The percentage of time in glucose range (glucose level between 140-199 mg/dl)

    Time frame: 30 months

  31. The percentage of time in glucose range (glucose level above 200 mg/dl)

    Time frame: 30 months

  32. Burned calories

    Mean and standard deviation of burned calories measures by activity and sleep tracker device.

    Time frame: 30 months

  33. Steps

    Mean and standard deviation of steps measures by activity and sleep tracker device.

    Time frame: 30 months

  34. Distance

    Mean and standard deviation of distance measures by activity and sleep tracker device.

    Time frame: 30 months

  35. Minutes null activity

    Mean and standard deviation of minutes null activity measures by activity and sleep

    Time frame: 30 months

  36. Minutes slight activity

    Mean and standard deviation of minutes slight activity measures by activity and sleep

    Time frame: 30 months

  37. Minutes mean activity

    Mean and standard deviation of minutes mean activity measures by activity and sleep tracker device.

    Time frame: 30 months

  38. Minutes high activity

    Mean and standard deviation of minutes high activity measures by activity and sleep tracker device.

    Time frame: 30 months

  39. Calories

    Mean and standard deviation of calories measures by activity and sleep tracker device.

    Time frame: 30 months

  40. Minutes asleep

    Mean and standard deviation of minutes asleep measures by activity and sleep tracker

    Time frame: 30 months

  41. Minutes awake

    Mean and standard deviation of minutes awake measures by activity and sleep tracker

    Time frame: 30 months

  42. Bed time

    Mean and standard deviation of bed time measures by activity and sleep tracker device.

    Time frame: 30 months

  43. Number time awake

    Mean and standard deviation of number time awake measures by activity and sleep

    Time frame: 30 months

07

Study locations

1 site
  • Institut d'Investigació Biomèdica de Girona (IDIBGI)
    Girona, Girona 17007, Spain
08

References and documents

Publications

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  • Fernandez-Real JM, Blasco G, Puig J, Moreno M, Xifra G, Sanchez-Gonzalez J, Maria Alustiza J, Pedraza S, Ricart W, Maria Moreno-Navarrete J. Adipose tissue R2* signal is increased in subjects with obesity: A preliminary MRI study. Obesity (Silver Spring). 2016 Feb;24(2):352-8. doi: 10.1002/oby.21347. Epub 2015 Dec 26. PubMed 26813526 ↗
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09

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Mar 31, 2026, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT05345106
Lead sponsor
Institut d'Investigació Biomèdica de Girona Dr. Josep Trueta
Responsible party
José Manuel Fernández-Real (Principal investigator, clinical professor, section chief of Endocrinology and Nutrition Department of Josep Trueta University Hospital, Institut d'Investigació Biomèdica de Girona Dr. Josep Trueta) — Principal investigator
First posted
Apr 25, 2022
Start date
Mar 28, 2022
Primary completion
Jan 22, 2026
Completion
Jan 31, 2027 (estimated)
Last update
Mar 31, 2026

Study contacts

José Manuel Fernández-Real, M.D., Ph.D.
principal investigator · Institut d'Investigació Biomèdica de Girona Dr. Josep Trueta

Oversight

FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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