A Relationship Between Human Microbiota and Diabetes and Effective Strategies Influencing the Features of Gut Microbiota

: The human body provides an environment in which trillions of microorganisms called “microbiome” exist. The diversity, composition, and function of these organisms depend on their body sites. The gut microbiota, a dense microbial community in the gastrointestinal (GI) tract, is thought to contain 100 times more genes than the human genome. Therefore, there should be a significant bidirectional relationship between gut microbiota and the human body. Normal gut microbiota performs several functions, keeping our body in a balanced situation, including immune system training, well-digesting nutrients, modulating the gut barrier, and producing essential molecules, such as neurotransmitters, hormones, and vitamins. Diabetes mellitus, a growing crisis, has involved many individuals in different age groups all around the world and has been significantly affected by these GI inhabitants' dysbiosis. Since some determining factors causing changes in the profile of gut microbiota are prebiotics, probiotics, and synbiotics, there have been considered a novel strategy for balancing these microorganisms and yet preventing metabolic diseases, one of which is diabetes. Scrutinizing the pathophysiology of diabetes mellitus, old methods of treating diabetes, such as acarbose, repaglinide, insulin pump therapy (IPT), and multiple daily injections (MDI) therapy, have been studied and optimized to be patient-based, resulting in a better yet effective treatment. In this review, key elements affecting the profile of gut microbiota, the etiology of diabetes, and the connection between human microbiota and diabetes, different indications of old and new strategies, and a few clinical types of research on changes occurring in diabetic patients in comparison to non-diabetic individuals have been elucidated.