Contributed by Carol Huang
Metabolic disease diabetes and obesity have impacted quite some percentage of the population, over 600 million people in the world are obese, and over 400 million have diabetes. Type I diabetes often involves the loss of beta islet cells which produce insulin; Type II diabetes is a disorder of elevated blood glucose levels (hyperglycemia) primarily due to insulin resistance and inadequate insulin secretion. Obesity contributes to T2D by decreasing insulin sensitivity in adipose tissue, liver, and skeletal muscle, and subsequently impaired beta-cell function, but not all obese individuals will develop type II diabetes.
Scientists have devoted plenty of efforts to understand the complex interaction of genes and environment involved. The gut microbiome is one of the factors that can play a role in diabetes risk. Therefore more and more attention has been drawn to study of the gut microbiota. There’s an old saying “All disease begins in the gut”. The gut microbiota is a collection of the microbial community in the gut, and the gut microbiome is the full collection of genes in the gut microbiota.16S rRNA gene sequencing created phylogenetic information to distinguish microbial groups in phylotypes but it lacks specificity to describe bacterial species for identifying the diverse composition of microbes (personal microbiota), while more advanced techniques like metagenomic sequencing would provide more sufficient and personalized information for the needs.
Gut microbiota has the function to communicate with each other, balance host immune system, depredate indigestible components in host diet, harvest energy and nutrition. Microbial population diversity and density vary along the gastrointestinal (GI) tract. Low bacterial diversity impairs the gut integrity causing low-grade inflammation through endotoxemia, which plays a profound role in the innate immune system in insulin resistance. Increased Gram-negative bacterial strains have also been seen in T2D patients “Diabetes and obesity are both associated with less diversity and less redundancy in the gut microbiome,” says Dr. Mathur. Diet is a major source of substrates for the production of small molecules by the gut microbiota. Diet change could significantly alter gut microbiota composition in 48 hours. Fecal samples are more representative for gut microbiome studies, which considered to be the full collection, therefore samples collection time, patient treatment and samples processing are critical, which will have a great impact on final conclusion.
Reference
The Gut Microbiome as a Target for the Treatment of Type 2 Diabetes. Ömrüm Aydin1,2& Max Nieuwdorp2,3,4 & Victor Gerdes1,2 Published online: 21 June 2018, Current Diabetes Reports (2018) 18: 55 https://doi.org/10.1007/s11892-018-1020-6
