Effect of a Postbiotic Intake on Glucose Control and Microbiota Composition of Type 2 Diabetic Subjects: a Randomized Controlled Trial.

The goal of this randomized clinical trial is to evaluate the effect of the administration of a postbiotic on glycemic control, insulin resistance and microbiota composition in subjects with type 2 diabetes.

The main questions it aims to answer are:

* Study the evolution of biochemical variables related to glycemic metabolism: basal glucose, basal insulin, glycemic variability through sensors, glycosylated hemoglobin (HbA1c), HOMA-IR index, C peptide.
* Perform a metagenomic analysis of intestinal microbiota in stool samples.
* Perform a metabolomics analysis on blood samples.
* Analyze the genetic profile in blood.
* Evaluate the evolution of biochemical variables related to lipid metabolism: total serum cholesterol, HDL-cholesterol, LDL-cholesterol and triglycerides.
* Assess the evolution of variables related to liver function: transaminases (ALT/AST).
* Analyze the evolution of the blood count.
* Evaluate the evolution of anthropometric variables (weight, height, waist and hip) and body composition.
* Analyze the evolution of blood pressure.
* Analyze eating and physical activity habits.
* Evaluate adherence to treatment and adverse events.
* Personalization on the use of postbiotics and other nutritional recommendations based on the genetic profile and the identification of patient clusters.

For this purpose, a randomized, double blind parallel study has been designed.

Target sample size is 158 subjects.

Participants will be allocated in two groups for 12 weeks:

* Experimental group (n=79): daily consumption of one postbiotic capsule.
* Placebo group (n=79): daily consumption of one placebo capsule.

Researchers will compare the consumption of a postbiotic supplement to a placebo.

Participants will visit nutritional intervention unit at week 0, week 2, week 10 and week 12 of the study.

Volunteers who wish to participate in the study will be interviewed by phone to verify that they meet the main inclusion criteria. Volunteers who meet the main inclusion criteria will be invited to an information and screening visit to resolve any doubts. Volunteers who agree to participate in the study will sign the informed consent and will be randomly allocated to one of the two arms of the study and will be provided with any required material.

During the intervention, volunteers will attend 4 Clinical investigation visits. The first one will be carried out on the first day of the study and the last one will take place at the end of the 12 weeks. In both visits anthropometric and body composition measurements, blood pressure, stool and blood samples, as well as data about dietary, physical activity and gastrointestinal symptoms will be taken. In the second and the third visits anthropometric, body composition, blood pressure and a blood sample will be taken. In the first and the third visits glucose monitoring sensor will be put and in the second and the fourth visits this glucosae monitoring sensor will be retired.

Eligibility Criteria:
Inclusion Criteria:

* Men and women aged between 18 and 70 years.
* Subjects diagnosed with DM2: glycosylated hemoglobin (HbA1c) ≥6.5% and/or basal glucose ≥126 mg/dL. Debut time will not be taken into account.
* Body Mass Index (BMI) between 25 and 39.9 kg/m2.
* Treatment for DM2/stable lifestyle, as well as other treatments for other pathologies (stable at least 3 months prior to the start of the intervention).
* Stable baseline HbA1c or glucose value for at least 3 months before starting the intervention.
* No weight variations (± 5%) during the last 3 months.
* Subjects must be in general physical and psychological conditions that the researcher assesses in accordance with the objective of the study.
* Subjects must be able to understand and be willing to sign the informed consent, and must comply with all study procedures and requirements.

Exclusion Criteria:

* Subjects who have received oral antibiotic treatment in the 45 days prior to the start of the study.
* Patients who have started hypoglycemic treatment, especially in the 3 months prior to inclusion. Insulin treatment.
* Severe untreated dyslipidemia, hypertension or hypothyroidism, or treated for less than 3 months.
* Presence of relevant functional or structural anomalies of the digestive system, such as malformations, angiodysplasias, active peptic ulcers, chronic inflammatory diseases or malabsorption.
* Subjects who have undergone surgical interventions of the digestive system with permanent consequences (for example, gastroduodenostomy).
* Suffer from any type of cancer or be undergoing treatment for it, or a period of less than 5 years since its eradication.
* Subjects who work rotating shifts that include night shifts.
* Presence of some type of psychological impediment such as depressive pathology, anxiety, untreated bipolar disorder. They will be able to participate if they have the disease but with stable treatment for at least 3 months prior to the start of the trial.
* Have an allergy or intolerance to any food or food group that is likely to manifest during the study.
* Be on a special diet during the 3 months prior to the start of the study, except for treatment for DM2, in this case, the lifestyle/diet will have to be stable in the 3 months prior to the start of the study.
* Weight variations (± 5%) during the last 3 months.
* Suffer from eating disorders or present restrictive behaviors in their diet. Score on the EAT-26 questionnaire equal to or greater than 20.
* Subjects who have undergone surgical treatment for obesity.
* Be pregnant or breastfeeding.
* Present alcohol abuse (more than 14 units/day in women and 20 units/day in men) and/or drugs.
* Show poor collaboration or have difficulties to follow the study procedures.
* Take some type of nutritional supplementation that can affect blood glucose and/or the microbiota. If they take it, in order to be included in the study, they will have to stop the supplement, with a washout period of at least 14 days before starting the study.