In recent years, the global rise in obesity and type 2 diabetes has become a major public health issue. In New Caledonia, 38% of the adult population has a body mass index ≥30. At the same time, the prevalence of type 2 diabetes continues to rise steadily. The burden of these diseases does not affect communities uniformly. While known factors such as diet, physical activity, and socioeconomic conditions play a role, studies have demonstrated the involvement of the gut microbiota in the development of metabolic disorders, particularly obesity and insulin resistance. However, this area remains largely unexplored in New Caledonia and the Pacific.

The goal of the study is to describe and characterize the gut microbiota and fecal metabolome of participants and study the relationships between microbiota composition and bioclinical parameters in participants with different metabolic states, ranging from "metabolically healthy" to severe obesity with and without type 2 diabetes.

To achieve this goal, adults in New Caledonia divided in 3 groups

1. Obese group with a BMI ≥ 30 with type 2 diabetes,
2. Obese group with a BMI ≥ 30 without any type of diabetes,
3. Control group of participants with a BMI between 18.5 and 24.9 kg/m2 and without any type of diabetes.

will be recruited. Blood, urine, and stool samples will be collected from participants. A questionnaire to collect sociodemographic characteristics as well as behaviors and lifestyle habits related to diet, physical activity, and psychological health.

Inclusion Criteria:

• Aged between 18 and 60 years.
• Ability to understand and provide informed consent.
• Ability and willingness to meet the required schedule and study interventions.
• Willingness to share their community belonging
• Benefit from a social security system.

For obese and diabetic patients :

• IMC ≥ 30 kg/m² with type 2 diabetes
• Fasting plasma glucose (FPG) ≥7 mM (=1.26g/l) or
• Patients with HbA1c ≥ 6.5% (48 mmol/mol)
• All stages of albuminuria For obese patients without type 2 diabetes
• IMC ≥ 30 kg/m²
• Weight stable for at least 2 months
• Patients with normal glucose tolerance (NGT), impaired glucose tolerance (IGT) and/or impaired fasting glucose (IFG) and an HbA1c < 6.5 %
• No treatment (diabetic or weight loss)
• Match age (±5years), sex and self-reported community to the patients from the1 group.

For control group :

• BMI between 18.5-24.9 kg/m²
• Match age (±5years), sex and self-reported community to the patients from the 1 and 2 groups.
• Participants with normal glucose tolerance (NGT), impaired glucose tolerance (IGT) and/or impaired fasting glucose (IFG) and an HbA1c < 6.5 %

Exclusion Criteria:

All participants :

• Treatment that may alter gastrointestinal motor function, acidity, microbial population, or immunosuppressants
• Altered anatomy of the esophagus, stomach, small intestine, or large intestine due to gastrointestinal surgery (except appendectomy or cholecystectomy)
• Chronic or acute inflammatory bowel disease or infections
• Abdominal or pelvic radiation therapy or abdominal cancer, colorectal cancer
• Dysphagia, eosinophilic esophagitis, esophageal stricture, or other swallowing disorders
• Organ transplantation and patients receiving immunosuppressive therapy
• Severe renal failure and/or patients undergoing dialysis
• Cardiovascular, endocrine, renal, or other chronic disease that may affect motility.
• Preparation for colon cleansing within the last month
• < 3 bowel movements per week
• Women who are pregnant or breastfeeding

Adults living in New Caledonia who are obese with or without type 2 diabetes or healthy