Examining the gut bacteriome, virome, and mycobiome in glucose metabolism disorders: Are we on the right track?

Human gut microbiome is defined as the gene complement of the gut microbial community, measured via laboratory metagenomic techniques. It includes bacteriome, virome and mycobiome, which represent, respectively, the assemblages of bacteria, viruses and fungi, living in the human gut. Gut microbiota function as a living "organ" that interacts with the gastro-intestinal environment, provides nutrients and vitamins to the organism and transduces hormonal messages, essentially influencing the main metabolic pathways, including drug metabolism. A clear association between gut, and glucose metabolism disorders has recently emerged. Medications acting on glucose absorption in the gut, or enhancing gut hormone activity are already extensively employed in the therapy of diabetes. Moreover, the gut is characterized by immune, and autonomous neuronal features, which play a critical role in maintaining glucose metabolism homeostasis. Gut microbes respond to neuroendocrine, and immune biochemical messages, affecting the health, and behavior of the host. There is vast heterogeneity in the studies included in this review, hence a meta-analysis, or a systematic review were not applicable. In this article, we attempt to reveal the interplay between human gut microbiota physiology, and hyperglycemic states, synthesizing, and interpreting findings from human studies.