Gut Microbiomes, Inflamation, Insulin Resistance, Type 2 Diabetes Mellitus (T2DM)
Conditions
Keywords
Type 2 Diabetes Mellitus, Insulin Resistance, Inflamation, Metabolic Syndrome, Physical Exercise, Gut Microbiome, Plant-based Diet, Lifestyle Interventions
Brief summary
The study evaluates the impact of a strict vegetarian diet combined with regular physical exercise and the use of probiotics on metabolic, inflammatory, and epigenetic parameters in patients with type 2 diabetes. It aims to determine the influence of these interventions on gut microbiota, glycemic control, body composition, insulin resistance, and quality of life.
Detailed description
This randomized, double-blind, placebo-controlled clinical trial aims to evaluate the effects of a strict vegetarian diet (SVD) combined with regular physical exercise (RPE), with or without probiotic supplementation, on key metabolic and physiological parameters in patients with type 2 diabetes mellitus (T2DM). Participants will be monitored for changes in glycemic control, insulin resistance (IR), liver function (elastography and ultrasound), metabolomic profile, muscle composition (biopsy), cholesterol efflux, and gene expression. Glycemic Control Glycemic control will be assessed through glycated hemoglobin (HbA1c), fasting glucose, fructosamine, and oral meal tolerance test (OMTT). A standardized dietary test (500 kcal plant-based meal) will be conducted at baseline and post-intervention, measuring postprandial glucose, insulin, proinsulin, C-peptide, and incretin hormones (GLP-1, GIP). Insulin Resistance (IR) IR will be evaluated using HOMA-IR (Homeostatic Model Assessment of Insulin Resistance) and fasting insulin levels. The study will also analyze inflammatory markers (TNF-α, IL-1β, IL-6, IFN-γ), as chronic low-grade inflammation plays a crucial role in IR development. Elastography and Ultrasound (US) Liver ultrasound and transient elastography (FibroScan®) will be performed to assess hepatic steatosis and fibrosis, which are highly prevalent in T2DM. The effects of dietary and probiotic interventions on liver fat content, liver stiffness, and metabolic liver function will be analyzed. Metabolome Analysis Metabolomic profiling will be conducted through mass spectrometry-based analysis of fasting and postprandial plasma samples. The study will evaluate amino acids, lipids, short-chain fatty acids, bile acids, ketone bodies, and glycolysis-related metabolites to understand how dietary and microbiome changes influence metabolic pathways in T2DM. Muscle Biopsy A vastus lateralis muscle biopsy will be performed in a subgroup of participants (n=24). Samples will be analyzed for fiber composition, extracellular matrix remodeling, mitochondrial function, and inflammatory markers. The role of microRNAs (miR-29a, miR-29b, miR-1, miR-133a/b, miR-206) in muscle insulin sensitivity will also be investigated. Cholesterol Efflux HDL functionality will be assessed by measuring cholesterol efflux capacity from macrophages exposed to participants' serum. This analysis will provide insight to cardiovascular risk modulation by diet and probiotics in T2DM. Gene Expression Analysis Peripheral blood lymphocytes will be analyzed for expression of inflammation-related genes (TNF-α, IL-6, IL-1β, IFN-γ, TLR4, TLR5) and longevity-related genes (SIRT1, FOXO1, PGC-1α, P53). These markers will help determine how dietary and probiotic interventions influence immune response, cellular aging, and metabolic regulation. Microbiota analysis This study will assess how a strict vegetarian diet and probiotic supplementation influence gut microbiota composition and functionality in individuals with T2DM. Stool samples will be collected before and after the intervention (4 weeks) and analyzed using 16S rRNA sequencing (NGS platforms: Ion Torrent PGM or Illumina MiSeq). Microbiota diversity (alpha and beta diversity metrics) and the relative abundance of key bacterial taxa (Bacteroides, Firmicutes, Akkermansia, Prevotella, Bifidobacterium, Lactobacillus) will be evaluated. Functional analysis will include metagenomic predictions (PICRUSt2), short-chain fatty acid (SCFA) production, and microbial metabolic pathways. The impact of probiotic supplementation (B. breve BR03, B. breve B632, B. longum 04, L. reuteri LRE11) will be assessed by comparing gut microbiota changes between the probiotic and placebo groups, focusing on butyrate-producing bacteria, lactate-utilizing species, and intestinal barrier integrity markers. The intervention will last four weeks, followed by 12 months of telemedicine follow-up. This study aims to provide new insights into the role of lifestyle interventions in metabolic regulation, inflammation, and gut microbiota modulation in T2DM, potentially offering novel therapeutic strategies beyond pharmacological approaches.
Interventions
DIETARY_SUPPLEMENTProbiotic Supplementation
Participants will follow the same strict vegetarian diet and regular physical exercise as in Intervention 1. Additionally, they will receive a probiotic supplement, taken twice daily for four weeks. This aims to evaluate the metabolic impact of probiotics in type 2 diabetes.
DIETARY_SUPPLEMENTPlacebo Administration
Participants will follow a strictly plant-based diet rich in fiber and bioactive compounds, with controlled macronutrient distribution. Regular physical exercise includes supervised aerobic and resistance training sessions. The intervention lasts four weeks. Instead of probiotic supplementation, participants will receive a placebo, administered in the same manner as the probiotic group to maintain blinding.
Sponsors
Clínica e Spa Vida Natural
Probiotical Spa
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Maria Elizabeth Rossi da Silva
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Intervention model description
This is a double-blind, placebo-controlled, randomized clinical trial. Patients will be informed about the type of therapy they will receive at the clinic, which includes a strict vegetarian diet and regular physical exercises, as well as the importance of adhering strictly to the prescribed instructions. A total of 60 patients will be recruited, with a maximum of six participants per four-week cycle. They will be randomized and allocated to the following treatment groups: Group 1: Strict vegetarian diet (SVD) + regular physical exercise (RPE) (n=30). Group 2: SVD + RPE + administration of a probiotic pool (n=30).
Eligibility
Sex/Gender
ALL
Age
45 Years to 70 Years
Healthy volunteers
No
Inclusion criteria
* Have a medical diagnosis of type 2 diabetes for a maximum of 5 years. * Be omnivorous; Have a Body Mass Index (BMI) ≥ 25 kg/m2 and \< 40 kg/m2; * Be between the ages of 45 and 70, both genders. * Women should be in the postmenopausal stage; * Use no more than three hypoglycemic medications in total; * Have the availability for a four-week consecutive hospitalization at CSVN.
Exclusion criteria
* Be using insulin, anti-obesity medications, antibiotics, and/or probiotic supplements in the 2 months preceding data collection; * Use of alcohol or tobacco; * Have limited mobility and a previous diagnosis of cardiopulmonary diseases; * Report current or previous (within the past two months) diarrhea during screening; * Have liver or kidney failure and uncontrolled endocrine disorders (hypothyroidism, hypogonadism, and adrenal insufficiency); * Have eating disorders or have undergone bariatric surgery.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Body Mass Index (BMI) | Baseline and 4 weeks post-intervention | Body mass index (BMI) will be calculated from height and weight (weight in kg / height in m²) to assess the impact of the intervention on overall body weight regulation. This outcome reflects metabolic improvement and lifestyle adherence. Unit of Measure: kg/m² |
| Change in Waist, Abdominal, and Hip Circumference | Baseline and 4 weeks post-intervention | Waist, abdominal, and hip circumferences will be measured using a standardized flexible tape method. These anthropometric parameters are indicators of central fat distribution and associated cardiometabolic risk. Measurements will follow WHO recommendations. Unit of Measure: cm |
| Change in Waist-to-Hip Ratio (WHR) | Baseline and 4 weeks post-intervention | Waist-to-hip ratio (WHR) will be calculated by dividing waist circumference by hip circumference. This index is used to evaluate body fat distribution and the risk of metabolic disorders, particularly central obesity, in individuals with T2DM. Unit of Measure: Ratio (unitless) |
| Change in Functional Aerobic Capacity (1-Mile Walk Test) | Baseline and 4 weeks post-intervention | Aerobic capacity will be assessed using the 1-Mile Walk Test. Participants will be instructed to walk one mile as fast as possible on a flat surface, and the time to completion will be recorded. The objective is to evaluate improvements in cardiovascular endurance following the intervention. Unit of Measure: Time in minutes |
| Change in Functional Mobility (Up and Go Test) | Baseline and 4 weeks post-intervention | Functional mobility will be assessed using the Up and Go test. Participants will be timed as they rise from a seated position, walk three meters, turn around, walk back to the chair, and sit down. The test is used to detect improvements in balance, mobility, and lower-limb function in response to the intervention. Unit of Measure: Time in seconds |
| Change in Fasting Blood Glucose | Baseline and 4 weeks post-intervention | Fasting plasma glucose will be measured after 8-12 hours of fasting by glucose-oxidase method to evaluate improvements in basal glycemic levels. The goal is to determine whether the intervention improves glucose homeostasis in patients with T2DM. Unit of Measure: mg/dL |
| Change in Postprandial Glucose Levels | Baseline and 4 weeks post-intervention | Two-hour postprandial glucose will be measured using capillary or venous blood samples by glucose-oxidase method after a standardized meal. The goal is to evaluate improvements in glycemic response to food intake due to the intervention. Unit of Measure: mg/dL |
| Change in Glycated Hemoglobin (HbA1c) | Baseline and 4 weeks post-intervention | Glycated hemoglobin (HbA1c) levels will be measured in venous blood samples using HPLC to assess long-term glycemic control. The main hypothesis is that the combined intervention of a plant-based diet, physical exercise, and probiotics will significantly reduce HbA1c levels compared to baseline. Unit of Measure: % HbA1c |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in Inflammatory Gene Expression in Lymphocytes and Skeletal Muscle | Baseline and 4 weeks post-intervention | Expression of genes encoding inflammatory mediators will be assessed by RT-qPCR in samples from peripheral blood lymphocytes and skeletal muscle. Expression will be reported as fold change compared to baseline. Unit of Measure: Fold change |
| Change in Fasting Insulin, Proinsulin, and C-Peptide Levels | Baseline and 4 weeks post-intervention | Fasting serum levels of insulin, proinsulin, and C-peptide will be measured using specific immunoassays. These markers collectively provide information about pancreatic β-cell function, insulin secretion, and metabolic status in patients with T2DM. Measurements will assess the effect of the intervention on pancreatic hormone production and secretion. Unit of Measure: ng/mL |
| Change in Insulin Resistance Assessed by HOMA-IR | Baseline and 4 weeks post-intervention | Insulin resistance will be evaluated using the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR), calculated from fasting glucose and insulin concentrations. Higher HOMA-IR values indicate greater insulin resistance. Unit of Measure: Index value (unitless) |
| Change in Incretin Hormone Levels (GLP-1 and GIP) | Baseline and 4 weeks post-intervention | Fasting plasma levels of the incretin hormones GLP-1 and GIP will be assessed using ELISA assays. These hormones play essential roles in glucose homeostasis by enhancing insulin secretion. Unit of Measure: pmol/L |
| Changes in Gut Microbiota Composition | Baseline and 4 weeks post-intervention | Microbial composition will be analyzed by 16S rRNA sequencing of fecal samples. Outcomes include alpha- and beta-diversity indices and the relative abundance (%) of specific bacterial taxa. These analyses aim to assess the impact of the dietary and probiotic intervention on gut microbiota in T2DM patients. Unit of Measure: Diversity index, % abundance |
| Change in Liver Steatosis Assessed by Abdominal Ultrasound | Baseline and 4 weeks post-intervention | Hepatic steatosis will be assessed using abdominal ultrasound performed by trained radiologists. Ultrasound evaluation will classify the degree of steatosis based on echogenicity criteria (mild, moderate, or severe). The purpose is to monitor the presence and severity of hepatic fat infiltration among participants with T2DM and to evaluate their response to the intervention. Unit of Measure: Steatosis grade (mild, moderate, severe) |
| Change in Liver Fat and Fibrosis Assessed by Transient Elastography | Baseline and 4 weeks post-intervention | Hepatic fat content and liver stiffness will be evaluated by transient elastography (FibroScan) to assess changes in hepatic steatosis and fibrosis after the intervention. Measurements will be expressed in kilopascals (kPa). Unit of Measure: kPa |
| Change in Liver Enzymes (AST, ALT, GGT) | Baseline and 4 weeks post-intervention | Serum levels of liver enzymes (AST, ALT, GGT) will be measured using automated enzymatic assays to evaluate liver function and detect possible hepatocellular injury or metabolic improvements after the intervention. Unit of Measure: U/L |
| Change in Diabetes-Specific Quality of Life Measured by the Diabetes Quality of Life Measure (DQOL) | Baseline and 12 weeks post-intervention | Diabetes-specific quality of life will be assessed using the Diabetes Quality of Life Measure (DQOL), Brazilian version. The instrument contains 44 items divided into four domains: satisfaction, impact, social/vocational concerns, and diabetes-related concerns. Each item is rated on a 5-point Likert scale. The mean score ranges from 1 to 5, with higher scores indicating worse quality of life. Interpretation of the scores is as follows: * 1.0 to 2.0: Very good diabetes-related quality of life * 2.1 to 3.0: Moderate quality of life * 3.1 to 4.0: Poor quality of life * 4.1 to 5.0: Very poor quality of life Unit of Measure: Mean DQOL - Brazil score (range: 1-5; higher scores indicate worse outcomes) |
| Change in General Well-Being Measured by the Q8RN Questionnaire | Baseline and 12 weeks post-intervention | General well-being will be assessed using the Q8RN Questionnaire (Eight Natural Remedies Questionnaire), which evaluates eight dimensions of healthy lifestyle habits: nutrition, exercise, water intake, sunlight exposure, temperance, fresh air, rest, and trust in God. Each dimension is assessed through Likert-scale questions, generally rated from 0 to 4 or from 1 to 5, depending on the version. Participants indicate how frequently they engage in each behavior (e.g., never, rarely, sometimes, often, always). Scores for each dimension can be analyzed separately or summed into a global score. Interpretation: higher scores indicate better adherence to healthy lifestyle practices. The Q8RN results can be used to identify lifestyle areas needing improvement or to track changes over time following educational or health-promotion interventions. Unit of Measure: Total Q8RN score (range: 8-40; higher scores indicate better outcomes) |
| Change in Fasting Glucose During Telemedicine Follow-Up | Every 3 months over a 12-month follow-up period after the intervention | Fasting plasma glucose will be measured at each telemedicine follow-up visit (every 3 months) over one year to monitor glycemic control. Blood samples will be collected after at least 8 hours of fasting. The intervention aims to improve and maintain fasting glucose levels within target ranges for patients with T2DM. Unit of Measure: mg/dL |
| Change in HbA1c Levels During Telemedicine Follow-Up | Every 3 months over a 12-month follow-up period after the intervention | HbA1c will be measured at each telemedicine follow-up to evaluate long-term glycemic control. Blood samples will be analyzed to determine the average blood glucose concentration over the preceding 2-3 months. The intervention aims to reduce and stabilize HbA1c levels. Unit of Measure: % HbA1c |
| Change in Lipid Profile During Telemedicine Follow-Up | Every 3 months over a 12-month follow-up period after the intervention | Serum lipid profile, including total cholesterol, LDL, HDL, and triglycerides, will be assessed at each telemedicine follow-up to monitor cardiometabolic health. These parameters reflect lipid metabolism and cardiovascular risk among patients with T2DM. Unit of Measure: mg/dL |
| Change in Liver Enzymes During Telemedicine Follow-Up | Every 3 months over a 12-month follow-up period after the intervention | Liver function will be monitored through serum levels of liver enzymes (AST, ALT, and GGT) measured every 3 months. This monitoring helps detect potential hepatic changes and the effect of the intervention on liver health. Unit of Measure: U/L |
| Change in Depressive Symptoms Measured by the Beck Depression Inventory - Second Edition (BDI-II) | Baseline and 12 weeks post-intervention | Depressive symptoms will be assessed using the Beck Depression Inventory - Second Edition (BDI-II), a 21-item self-report questionnaire. Each item is scored from 0 to 3, resulting in a total score ranging from 0 to 63. Higher scores indicate greater severity of depressive symptoms. Interpretation of the total score is as follows: 0-13: minimal depression; 14-19: mild depression; 20-28: moderate depression; 29-63: severe depression. Unit of Measure: Total BDI-II score (range: 0-63; higher scores indicate worse outcomes) |
| Change in Standard Lipid Profile | Baseline and 4 weeks post-intervention | Serum levels of total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides will be measured by enzymatic colorimetric assays. These parameters are essential for assessing cardiometabolic risk in patients with T2DM. Unit of Measure: mg/dL |
| HDL Function and Lipid Profile | Baseline and 4 weeks post-intervention | HDL function will be evaluated by measuring cholesterol efflux capacity in vitro using labeled macrophage assays. The result reflects HDL's ability to remove cholesterol from peripheral tissues, a key anti-atherogenic property. Unit of Measure: % cholesterol efflux |
| Change in C-Reactive Protein (CRP) Levels | Baseline and 4 weeks post-intervention | C-reactive protein (CRP), a marker of systemic low-grade inflammation and cardiovascular risk, will be measured in plasma using high-sensitivity Luminex assay. Unit of Measure: mg/L |
| Change in Plasma Cytokine Levels | Baseline and 4 weeks post-intervention | Plasma concentrations of proinflammatory cytokines TNF-α, IL-6, IL-1β, and IFN-γ will be measured using the Luminex multiplex assay. These markers are associated with systemic inflammation and insulin resistance in patients with T2DM. Unit of Measure: pg/mL |
| Metabolomic and Biochemical Markers | Baseline and 4 weeks post-intervention | Metabolomic profiling will assess amino acids, fatty acids, and glucose/lipid-related metabolites in plasma using mass spectrometry. Both fasting and postprandial samples will be analyzed. Unit of Measure: μmol/L |
| Change in expression of Metabolism- and Inflammation-Related microRNAs | Baseline and 4 weeks post-intervention | Expression levels of specific microRNAs involved in metabolic and inflammatory pathways will be measured in plasma and tissue samples by qPCR. Unit of Measure: Fold change |
| Change in Expression of Inflammatory Genes | Baseline and 4 weeks post-intervention | Gene expression of inflammatory markers will be analyzed in peripheral blood lymphocytes using NGS. Unit of Measure: Fold change |
Countries
Brazil
Contacts
Primary ContactMaria E. R. Silva, MD, PhD
Backup ContactEdna C. Vieira, Master of Science in Nutrition
Outcome results
None listed