A Systematic Review of the Effect of Probiotics, Prebiotics, and Synbiotics on Gut Microbiota in Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) occurrence and progression are attributed to the gut microbiota environment. Probiotics have a key role in epithelium proliferation, gut barrier stabilization, metabolic endotoxemia, gut permeability, and systemic inflammation. The aim of this study was to assess the gut microbiota-modulatory properties of probiotic, prebiotic, and synbiotic on zonulin, lipopolysaccharide (LPS), short-chain fatty acids (SCFA), lipopolysaccharide binding protein (LBP), and endotoxin in T2DM. A comprehensive search up to November 2023 was conducted in Web of Science, PubMed, and Scopus databases. The Cochrane Risk of Bias tool was selected for assessing the methodological quality and risk of bias of selected studies. The findings of 16 studies showed that probiotic, prebiotic, and synbiotic administration in T2DM patients was efficient in decreasing endotoxin and LPS, while there were no significant changes regarding LBP, and controversial results for SCFA and zonulin. Probiotic, prebiotic, and synbiotic administration is efficient in improving some aspects of gut microbiota integrity, gut immunity markers, and subsequently improving glucose homeostasis in T2DM patients. Nevertheless, multiple randomized controlled trials are warranted.