VITAMIN D AND PREBIOTICS MAY BENEFIT THE INTESTINAL MICROBACTERIA AND IMPROVE GLUCOSE HOMEOSTASIS IN PREDIABETES AND TYPE 2 DIABETES

Objective: To review the role of human large bowel microbacteria (microbiota) in the glucose homeostasis, to address vitamin D (VD) and prebiotics interactions with microbiota, and to summarize recent randomized clinical trials (RCTs) of VD and prebiotics supplementation in prediabetes (PreDM) and type 2 diabetes mellitus (T2DM). Methods: Primary literature was reviewed in the following areas: composition and activity of human microbiota associated with PreDM and T2DM, interactions between microbiota and glucose homeostasis, the interaction of microbiota with VD/prebiotics, and RCTs of VD/prebiotics in subjects with PreDM or T2DM. Results: The human microbiota is comprised of 100 trillion bacteria with an aggregate genome that is 150-fold larger than the human genome. Data from the animal models and human studies reveal that an "obesogenic" diet results into the initial event of microbiota transformation from symbiosis to dysbiosis. The microbial antigens, such as Gram(-) bacteria and lipopolysaccharide (LPS), translocate to the host interior and trigger increased energy harvesting and Toll-like receptor (TLR) activation with subsequent inflammatory pathways signaling. The "double hit" of steatosis (ectopic fat accumulation) and "-itis" (inflammation) and contribution of "corisks" (e. g., vitamin D deficiency [VDD]) are required to activate molecular signaling, including impaired insulin signaling and secretion, that ends with T2DM and associated diseases. Dietary changes (e. g., prebiotics, VD supplementation) may ameliorate this process if initiated prior to the process becoming irreversible. Conclusion: Emerging evidence suggests an important role of microbiota in glucose homeostasis. VD supplementation and prebiotics may be useful in managing PreDM and T2DM.