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CompletedNCT04841668SmartAgeUpdated Mar 31, 2026

Gut-Brain-axis: Targets for Improvement of Cognition in the Elderly

An observational study in Type 2 Diabetes Mellitus, sponsored by Institut d'Investigació Biomèdica de Girona Dr. Josep Trueta. Completed at 1 site in Spain. Open to participants aged 65 Years to 80 Years. Per ClinicalTrials.gov, last updated 2026-03-31.

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

Study type
Observational
Model
Cohort
Time perspective
Prospective
Enrollment
50
Ages
65 Years to 80 Years
Sex
All
01

Study summary

Cognitive disorders increase with age and in the presence of metabolic diseases such as Type 2 Diabetes Mellitus (T2DM). In addition, digestive disorders, changes in dietary pattern and decreased activity negatively influence the microbiome.

The hypothesis is that pharmacological intervention with metformin will modify the composition of the gut microbiota and cognition.

The study has a pilot longitudinal design, where each patient with T2DM will be followed for one year. Two groups will be recruited:

  1. Group A: The aim will be to evaluate the associations between glucose (measured by continuous glucose monitoring (CGM)), cognitive function (by means of cognitive tests and magnetic resonance imaging (MRI)), physical activity (recorded by activity and sleep tracker devicer), metformin, diet (evaluated by nutritional survey) and composition of the microbiota (evaluated by metagenomics), during 12 months (6 months without metformin and 6 months with metformin treatment).
  2. Group B: The aim will be to evaluate the associations between glucose, diet (evaluated by nutritional survey), cognitive function (by means of cognitive tests), physical activity (measured by activity and sleep tracker device), the treatment and composition of the microbiota (evaluated by metagenomics), during 12 months.
Read the detailed description

Subjects and methods:

Longitudinal study:

Patients with T2DM 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.

GROUP A

This study consists of an initial phase, where the patient will be submitted as the only treatment to a balanced diet with an energy intake, calculated individually according to whether he/she is normal weight (25 Kcal x Kg) or overweight (20 Kcal x Kg of weight).

After this initial phase, in addition to continuing with the balanced diet treatment, patients will start treatment with metformin administered orally at an initial dose of 425 mg/d every 12 hours during the first 15 days and then continue with doses of 850 mg/d until the end of the study.

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 FDA (Dexcom G6 ®). The sensor will be inserted on day 0 and it will retire on day 10 midmorning.

This process will be repeated 10 days prior to the start of the of treatment with Metformin and 10 days before the end of the 6 month study phase with metformin. During the study, 6 visits will be made and each patient will be inserted with a total of 3 glycemia sensors and 3 physical activity monitors. In summary, the glycemia sensor and physical activity monitoring will be started at visits 1, 3, 5 and will be removed at visits 2,4,6.

Visit 1(day 1): Physical examination, Nutritional survey, Bioimpedance, Densitometry, CGM and Activity and sleep tracker device. Consent form

Visit 2 (day 10): Sample: blood, urine and feces. Diet, Neuropsychological test, CGM withdrawal, Activity and sleep tracker device withdrawal, MRI.

Visit 3 (day 170): Physical examination, Nutritional survey, Bioimpedance, CGM and Activity and sleep tracker device

Visit 4 (day 180): Sample: blood, urine and feces. Dietary follow-up, Neuropsychological test, CGM withdrawal and Activity and sleep tracker device withdrawal. Start of metformin treatment.

Visit 5 (day 350): Physical examination, Nutritional survey, Bioimpedance, CGM and Activity and sleep tracker device.

Visit 6 (day 360): Sample: blood, urine and feces. Dietary follow-up, Neuropsychological test, CGM withdrawal and Activity and sleep tracker device withdrawal. Metformin withdrawal.

GROUP B:

During the study, 5 visits will be made for this group:

Visit 1(day 1): Physical examination, Nutritional survey, Bioimpedance, Densitometry and Activity and sleep tracker device. Consent form.

Visit 2 (day 10): Sample: blood, urine and feces. Diet, Neuropsychological test and Activity and sleep tracker device withdrawal.

Visit 3 (day 180): Diet follow-up.

Visit 4 (day 350): Physical examination, Nutritional survey, Bioimpedance and Activity and sleep tracker device.

Visit 5 (day 360): Sample: blood, urine and feces. Diet follow-up, Neuropsychological test and Activity and sleep tracker device withdrawal.

DATA COLLECTION OF SUBJECTS 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
    • 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 haemoglobin (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 intestinal microbiota in stool:

    • Determination of bacterial DNA and mRNA and study of the LBP binding protein in blood for the detection of bacterial translocation. LBP binding protein in blood for the detection of bacterial translocation. Hiseq and Nextseq technology (qPCR and protein analysis (WB, ELISA), OMICS (RNAseq, 16S, Metabolomics, Metagenomics).
    • Inflammatory and immunological markers will be determined using ELISA (enzyme-linked immunosorbent assay) and immunohistochemistry (IHC) equipment and quantitative real-time PCR validation. For qPCR, total RNA will be isolated from different tissues and will transcribe into cDNA.
    • Determination of metabolic profile and metabolite analysis.
  5. Intestinal barrier function:Exposure to a lactulose:mannitol test before/after surgery. Plasma samples will be used to measure intestinal permeability markers: bacterial endotoxin, sCD14, LBP, ZO-1, and I-FABP.
  6. 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.
  7. MRI: The necessary sequences will be acquired for the calculation of the BrainAGE biomarker and the characterization of the networks involved in cognitive functions. For the acquisition a 1.5 T scanner (Ingenia; Philips Medical Systems) will be used 1,5 T scanner (Ingenia; Philips Medical Systems) will be used for the acquisition. First, recovery-inversion sequence (T2-FLAIR) will be used to exclude subjects with pre-existing brain lesions. Subsequently, structural sequences will be acquired sequences will then be acquired to measure the integrity of cerebral gray matter (T1-weighted), tracts of weighted), of the white matter tracts (DTI), iron accumulation (R2*), and (R2*), and functional sequences in resting-state (T2*-weighted echo-planar imaging, EPI).
  8. 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). In addition, cognitive impairment will be evaluated with Lobo's Mini-Cognitive Exam. These tests will be useful to define the changes in the cognitive profile associated with the pharmacological intervention with metformin.

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

STATICAL METHODS:

Sample size: Since this is intended as a pilot study, no formal sample size calculation is required. A general rule is to recruit 30 or more patients to estimate a parameter and 15-20 participants per group to obtain reasonable estimates for medium to large effect sizes.

Statistical analyses: It will be based on a descriptive analysis (mean, standard deviation, sample size, median, minimum and maximum) of the quantitative parameters and the indication of the frequency of the remaining categorical parameters. Comparisons between groups will be based on a paired samples t-test or a chi-square test. The results of these analyses may be useful to assess whether further analyses are needed to adjust for possible imbalance in the baseline characteristics of the patients.

The changes in the composition of the gut microbiota after the intervention with metformin will be analyzed using Heatmaps, Principal Component Analysis (PCA) and PLSDA. For the multivariate statistical analysis (PLSDA and hierarchical clustering). The variables that comprise the characteristics of the intestinal microbiota and cognitive tests will be logarithmically transformed, filtered with interquartile range estimation and staggered by autoscale calculation (mean and divided by the standard deviation of each variable) by using the Metaboanalyst platform.

The changes determined in the gut microbiota and cognition variables will be explored in relation to the changes in the secondary variables (metabolic, metabolome, inflammation parameters) by linear regression analysis in SPSS. Brain image variables will be analyzed with specialized programs (MATLAB, SPM12).

02

Conditions studied

  • Type 2 Diabetes Mellitus

Keywords

  • Type 2 Diabetes Mellitus
  • Continous Glucose Monitoring
  • Cognition
  • Metformin
  • Gut microbiome
  • Magnetic resonance imaging
  • Physical activity monitor
03

In context

Diabetes Mellitus, Type 2

9,359 studies on the registry are indexed under Diabetes Mellitus, Type 2; 1,318 are open to participants now.

This study's enrollment of 50 is below the median of 300 across 1,588 observational studies indexed under Diabetes Mellitus, Type 2.

Browse Diabetes Mellitus, Type 2 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
65 Years to 80 Years
Sexes eligible
All
Accepts healthy volunteers
No
Sampling method
Non-probability sample

Study population

Group A Study population Adult patients (≥ 65 years of age) recently diagnosed with T2DM according to the WHO and who have not been treated with metformin.

Group B Study population Adult patients (≥ 65 years of age) diagnosed with long-term T2DM according to the WHO classification, regardless of whether they take metformin or other treatment.

Eligibility criteria

Group A

Inclusion Criteria:

  1. Age between 55 and 80 years.
  2. Patients with recently diagnosed T2DM (last 6 months), according to the WHO classification.
  3. Patients in whom written informed consent has been obtained for participation in the study.

Exclusion Criteria:

  1. HbA1c ≥ 9%
  2. Metformin treatment in the past 6 months
  3. Creatinine greater than 1.2 and glomerular filtration rate less than 40
  4. Serious systemic disease not related to obesity, including any type of cancer, severe kidney disease or liver disease, and known type 1 diabetes.
  5. Systemic diseases with intrinsic inflammatory activity such as rheumatoid arthritis, Crohn's disease, asthma, or chronic infection (e.g., HIV, active tuberculosis) or any type of infectious disease.
  6. Current treatment for malignant neoplasia, other than basal cell or squamous cell skin cancer.
  7. Class III or IV heart disease, known ischemic cardiovascular disease
  8. Kidney failure, history of kidney transplant, or current dialysis treatment
  9. Serum liver enzymes (GOT, GPT) above twice the upper limit of normal. Obvious signs or symptoms of liver disease, acute or chronic hepatitis.
  10. Chronic constipation (stool habit ≥ 7 days)
  11. Pregnancy or breastfeeding
  12. Treatments that affect glucose metabolism or the intestinal microbiota with biguanides, sulfonylurea secretagogues or non-sulfonylurea secretagogues, insulin sensitizers, insulin, thiazolidinediones, alpha glucosidase inhibitors, incretin mimetics, Dipeptidyl peptidase IV inhibitors, use of cathartics.
  13. Chronic anti-inflammatory treatment with steroidal drugs (during the previous 3 months).
  14. Symptoms and / or clinical signs of infection in the previous month.
  15. Antibiotic, antifungal or antiviral treatment active in the previous 3 months.
  16. Treatment with glucocorticoids chronic or during the 2 months prior to inclusion in the study.
  17. Treatment with a weight loss product during the previous two months
  18. Immunosuppressant treatment.
  19. Excessive alcohol consumption (alcohol intake greater than 40 g per day (women) or 80 g / day (men)) either acute or chronic, or drug use. History of drug or alcohol abuse.
  20. Patients with severe eating disorders
  21. History of alterations in iron balance (known chronic hemoglobinopathies or anemia, genetic hemochromatosis, hemosiderosis from any cause, atransferrinemia, paroxysmal nocturnal hemoglobinuria).
  22. Important psychiatric history.
  23. Participation in any other study.
  24. People whose freedom is under legal or administrative requirement.

Group B

Inclusion Criteria:

  1. Age between 65 and 80 years.
  2. Patients with long-term T2DM according to the WHO classification
  3. Patients in whom written informed consent has been obtained for participation in the study.

Exclusion Criteria:

  1. HbA1c ≥ 9%
  2. Creatinine greater than 1.2 and glomerular filtration rate less than 40
  3. Serious systemic disease not related to obesity, including any type of cancer, severe kidney disease or liver disease, and known type 1 diabetes.
  4. Systemic diseases with intrinsic inflammatory activity such as rheumatoid arthritis, Crohn's disease, asthma, or chronic infection (e.g., HIV, active tuberculosis) or any type of infectious disease.
  5. Current treatment for malignant neoplasia, other than basal cell or squamous cell skin cancer.
  6. Class III or IV heart disease, known ischemic cardiovascular disease.
  7. Kidney failure, history of kidney transplant, or current dialysis treatment
  8. Serum liver enzymes (GOT, GPT) above twice the upper limit of normal. Obvious signs or symptoms of liver disease, acute or chronic hepatitis.
  9. Chronic constipation (stool habit ≥ 7 days)
  10. Pregnancy or breastfeeding
  11. Chronic anti-inflammatory treatment with steroidal drugs (during the previous 3 months).
  12. Symptoms and / or clinical signs of infection in the previous month.
  13. Antibiotic, antifungal or antiviral treatment active in the previous 3 months.
  14. Treatment with glucocorticoids chronic or during the 2 months prior to inclusion in the study.
  15. Treatment with a weight loss product during the previous two months.
  16. Immunosuppressant treatment.
  17. Excessive alcohol consumption (alcohol intake greater than 40 g per day (women) or 80 g / day (men)) either acute or chronic, or drug use. History of drug or alcohol abuse.
  18. Patients with severe eating disorders
  19. History of alterations in iron balance (known chronic hemoglobinopathies or anemia, genetic hemochromatosis, hemosiderosis from any cause, atransferrinemia, paroxysmal nocturnal hemoglobinuria).
  20. Important psychiatric history.
  21. Participation in any other study.
  22. People whose freedom is under legal or administrative requirement.
05

Study design

Observational model
Cohort
Time perspective
Prospective
Enrollment
50 participants (actual)
Patient registry
No

Groups and cohorts

  • Patients with recently diagnosed T2DM

    This group will consist of 36 recently diagnosed T2DM, according to the World Health Organization (WHO) patients (last 6 months), who have not received treatment with metformin.

    Drug: Metformin

  • Patients with long-term T2DM

    The group will consist of 100 patients with long-term T2DM, according to the WHO classification, regardless of whether they take metformin or another treatment.

Interventions

  • DrugMetformin

    Patients will begin treatment with metformin administered orally at a starting dose of 425 mg / day every 12 hours for the first 15 days and then continue with a dose of 850 mg / day until the end of the study. The beginning of this treatment phase will be following the recommendations of the clinical guidelines (Comprehensive Approach to Type 2 Diabetes Mellitus, SEEN V2019.2)

06

What researchers measure

Primary outcomes

  1. Gut microbiota composition.

    It will be identified in the stool by cultures and DNA and mRNA expression after metformin treatment.

    Time frame: 12 months

  2. Cognitive impairment

    It will be measured by Mini-Examen Cognoscitivo (MEC).

    Time frame: 12 months

  3. Audioverbal memory

    It will be measured by Test aprendizaje verbal-TAVEC.

    Time frame: 12 months

  4. Visual memory

    It will be measured by Rey-Osterrieth Complex Figure.

    Time frame: 12 months

  5. Depressive symptomatology

    It will be measured by Patient Health Questionnaire-9 (PHQ-9).

    Time frame: 12 months

  6. Impulsivity

    It will be measured by UPPS Impulsive Behavior Scale.

    Time frame: 12 months

  7. Food Addiction

    It will be measured by Yale Food Addiction Scale.

    Time frame: 12 months

  8. Behavioral inhibition

    It will be measured by Sensitivity to Punishment and Sensitivity to Reward (SPSRQ).

    Time frame: 12 months

  9. Behavioral activation

    It will be measured by Sensitivity to Punishment and Sensitivity to Reward (SPSRQ).

    Time frame: 12 months

  10. Visoconstructive function

    It will be measured by Rey-Osterrieth Complex Figure.

    Time frame: 12 months

  11. Visuospatial perception

    It will be measured by Judgment Line Orientation.

    Time frame: 12 months

  12. Naming

    It will be measured by Boston Naming Test.

    Time frame: 12 months

  13. Selective and alternating attention

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

    Time frame: 12 months

  14. Attention and working memory

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

    Time frame: 12 months

  15. Inhibition

    It will be measured by Stroop Color-Word Test.

    Time frame: 12 months

  16. Phonemic verbal fluency

    It will be measured by PMR

    Time frame: 12 months

  17. Semantic verbal fluency

    It will be measured by Animals

    Time frame: 12 months

Secondary outcomes

  1. The percentage of time in glucose target range (glucose level 70mg/dl-180mg/dl)

    Time frame: 12 months

  2. Effect on gut microbiota

    Gut microbiota will be analysed by metagenomics and metabolomics.

    Time frame: 12 months

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

    Time frame: 12 months

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

    Time frame: 12 months

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

    Time frame: 12 months

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

    Time frame: 12 months

Other outcomes

  1. Integrity of the brain gray matter

    It will be assessed using magnetic resonance imaging (T1-weighted)

    Time frame: 12 months

  2. Integrity of the white matter tracts

    It will be assessed using magnetic resonance imaging with diffusion tensor imaging (DTI)

    Time frame: 12 months

  3. Brain iron accumulation

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

    Time frame: 12 months

  4. Resting-state functional brain sequences

    It will be assessed using magnetic resonance imaging (T2\*-weighted echo-planar imaging)

    Time frame: 12 months

  5. Insulin resistance

    It will be measured by HOMA

    Time frame: 12 months

  6. 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: 12 months

  7. Glycosylated hemoglobin (HbA1c) value

    Glycosylated hemoglobin (HbA1c) in % or mmol/mol

    Time frame: 12 months

  8. The percentage of time in hyperglycaemia (glucose level above 180 mg/dl)

    Time frame: 12 months

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

    Time frame: 12 months

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

    Low blood glucose index (LBGI) is a parameter that quantifies the risk of glycaemic excursions in non-negative numbers.

    Time frame: 12 months

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

    High blood glucose index (HBGI) is a parameter that quantifies the risk of glycaemic excursions in non-negative numbers.

    Time frame: 12 months

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

    measured in mg/dl

    Time frame: 12 months

  13. Burned calories

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

    Time frame: 12 months

  14. Steps

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

    Time frame: 12 months

  15. Distance

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

    Time frame: 12 months

  16. Plants

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

    Time frame: 12 months

  17. Minutes null activity

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

    Time frame: 12 months

  18. Minutes slight activity

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

    Time frame: 12 months

  19. Minutes mean activity

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

    Time frame: 12 months

  20. Minutes high activity

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

    Time frame: 12 months

  21. Calories consumption

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

    Time frame: 12 months

  22. Minutes asleep

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

    Time frame: 12 months

  23. Minutes awake

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

    Time frame: 12 months

  24. Bed time

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

    Time frame: 12 months

  25. Minutes light sleep

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

    Time frame: 12 months

  26. Minutes deep sleep

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

    Time frame: 12 months

  27. Minutes rapid eye movement (REM)

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

    Time frame: 12 months

  28. Number time awake

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

    Time frame: 12 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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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
NCT04841668
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 12, 2021
Start date
Apr 10, 2021
Primary completion
Dec 3, 2024
Completion
Dec 3, 2024
Last update
Mar 31, 2026

Study contacts

José M Fernández-Real, Ph.D.
principal investigator · Institut d'Investigació Biomèdica de Girona (IDIBGI)

Oversight

FDA-regulated drug
No
FDA-regulated device
No
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