Gut dysbiosis in diabetes mellitus is associated with decreased short-chain fatty acids and epithelial barrier disruption. Microbial-derived toxins move across the "leaky gut" and incur systemic inflammation and insulin resistance. In children, gut dysbiosis has been associated with risk of developing type 1 diabetes mellitus. In animal models, the obesity phenotype is transferable via microbiota transplantation. Plant-based low protein diets and certain anti-diabetic drugs have been associated with positive microbiome effects. Clinical trials with prebiotics and probiotics have yielded mixed results. Further investigations are needed to evaluate the gut microbiome as a potential therapeutic target for diabetes prevention and management.