GUT MICROBIOTA AS A THERAPEUTIC TARGET IN OBESITY AND TYPE 2 DIABETES MELLITUS

Obesity and type 2 diabetes mellitus (T2DM) are increasing worldwide, and gut microbial features are repeatedly associated with adiposity, insulin resistance and low-grade inflammation. This structured narrative review evaluates whether those associations support therapeutic use. PubMed/MEDLINE, Google Scholar, Clinical Trials.gov and authoritative regulatory or guideline sources were searched for English-language literature published from January 2004 to 17 July 2026. Evidence was classified as experimental, observational, randomized clinical trial or systematic review/meta-analysis. Animal studies support mechanisms involving intestinal permeability, short-chain fatty acids, bile-acid signalling and host-microbial co-metabolism, but these findings cannot be assumed to produce clinical benefit. In humans, dietary fibre and selected prebiotic, probiotic or synbiotic products may produce small, heterogeneous improvements in glycaemia or adiposity. Preparation-specific trials of Akkermansia muciniphila are promising, particularly for pasteurized products, but live, pasteurized and protein-based preparations are not interchangeable and none is an approved treatment for obesity or T2DM. Fecal microbiota transplantation remains experimental for metabolic disease because engraftment is variable, metabolic outcomes are inconsistent and infection-transmission risk requires rigorous donor screening. Microbiota changes after bariatric surgery, metformin, acarbose or berberine may contribute to response but do not replace their established direct mechanisms. Microbiota-directed strategies should therefore be regarded as adjunctive or investigational, with future trials requiring strain or product identification, dose standardization, adequate power, longer follow-up and clinically meaningful endpoints.