Abstract
BACKGROUND: Polycystic ovary syndrome (PCOS) and type 2 diabetes mellitus (T2DM) are interrelated through insulin resistance (IR) and gut microbiota dysbiosis. This review evaluates the synergistic efficacy and mechanisms of a combined probiotic and metformin regimen in the management of PCOS, with a specific focus on the gut-ovary-metabolism axis. METHODS: A systematic literature search was conducted following PROSPERO (ID: CRD420251143914) registration across PubMed, EMBASE, Web of Science, the China National Knowledge Infrastructure (CNKI), the Wanfang Database, and the VIP Database, prioritizing randomized controlled trials and retrospective studies. RESULTS: The combination therapy suggests improved outcomes compared to metformin monotherapy, yielding significant improvements in metabolic, hormonal, and reproductive function. Crucially, probiotics alleviated metformin-induced gastrointestinal adverse effects, thereby enhancing treatment adherence. The proposed underlying mechanisms involve a synergistic restoration of gut microbial homeostasis, increased production of short-chain fatty acids, reinforcement of the intestinal barrier, and potentiated activation of the AMP-Activated Protein Kinase (AMPK) pathway. CONCLUSION: As an adjunct supplement to metformin, probiotics represent a novel, evidence-supported therapeutic strategy for PCOS. This approach offers enhanced efficacy and tolerability, with potential implications for a broader spectrum of metabolic disorders including T2DM; however, given the current paucity of related studies, conclusions should be drawn cautiously. SYSTEMATIC REVIEW REGISTRATION: [https://www.crd.york.ac.uk/prospero/], identifier [CRD420251143914].