Dietary Fibers and Prebiotics for Gut Microbiota Modulation in Type 2 Diabetes: Mechanisms and Therapeutic Potential

Background: Type 2 diabetes mellitus (T2DM) is a prevalent metabolic disorder in which gut microbiota dysbiosis contributes to insulin resistance, metabolic inflammation, and impaired glucose homeostasis. Dietary fibers and prebiotics selectively modulate gut microbiota composition and function and may offer metabolic benefits in T2DM. This review examines the mechanistic links between dietary fibers, prebiotics, gut microbiota modulation, and metabolic outcomes in T2DM. Methods: Relevant experimental and clinical studies were reviewed to assess the effects of dietary fibers and prebiotics on microbial diversity, short-chain fatty acid production, intestinal barrier function, bile acid signaling, and glycemic control in T2DM. Results: Evidence indicates that T2DM is associated with reduced abundance of SCFA-producing bacteria, increased intestinal permeability, metabolic endotoxemia, and altered bile acid metabolism. Dietary fibers and prebiotics enhance SCFA production, support gut barrier integrity, and modulate inflammatory and metabolic pathways. Clinical evidence demonstrates modest improvements in glycemic and inflammatory parameters, though outcomes vary according to fiber type, dose, and baseline microbiota composition. Conclusions: Dietary fibers and prebiotics are promising, low-risk strategies for gut microbiota modulation in T2DM. Further standardized, long-term randomized studies integrating microbiome profiling and clinically meaningful endpoints are required to support precision nutrition approaches.