The number of patients with obesity and type 2 diabetes (T2D) is increasing at an alarming rate in both developed and developing countries. The World Health Organization (WHO) has recognised diabetes and obesity as the first non-infectious epidemic. According to WHO findings from 07.04.2016, over 422 million people in the world have diabetes and every tenth person is obese .It is also worrying that the problem of diabetes and obesity is increasingly affecting children and adolescents. Despite the significant progress in medicine, no effective means of combating these diseases have been found and forecasts for subsequent years predict that by 2040 the number of people with diabetes in the world will exceed 642 million

In the study of relationships between microbiota and obesity, type 2 diabetes, or other metabolic diseases, the main research tool is next-generation sequencing, where the baseline material subjected to the appropriate processing and metagenomic analyses is constituted by bacterial DNA isolates from faecal samples from patients. Therefore, the microbiota of the large intestine is quite well described. Some studies, however, suggest a different approach that assumes that this type of research should focus primarily on the small intestine microbiota .In the literature, microbiological analysis of upper parts tract, e.g., duodenum, especially in the progress of obesity or diabetes, is rarely the subject of discussion .

The main reason for the lack of work on this subject is the difficulty in accessing the proximal sections of the intestine since biopsy collection is associated with an invasive intervention that requires the use of a gastroscope. Other reasons are the acidic pH of the stomach and the presence of digestive enzymes that inhabit the small intestine that significantly reduce the number of microbial cells .Most literature data based on duodenal microbiota studies that can be found mainly concern paediatric patients with celiac disease.

The duodenal section of the gastrointestinal tract is located at the intersection between the stomach, secreting digestive enzymes, and the jejunum and ileum, which absorb nutrients. Due to its strategic position in the gastrointestinal tract, the duodenum has important functions related to the digestive process and the absorption of nutrients .Therefore, the structure of the microbiota within this section is worth investigating.

Regards,

Jessica

Managing editor

International journal of pure and applied zoology