MYO-INOSITOL AND D-CHIRO-INOSITOL IN POLYCYSTIC OVARY SYNDROME: MECHANISMS OF ACTION, CLINICAL EFFECTIVENESS, SAFETY, AND CURRENT LIMITATIONS: A NARRATIVE REVIEW

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Background Polycystic ovary syndrome (PCOS), for which the term polyendocrine metabolic ovarian syndrome (PMOS) has recently been proposed, is a common chronic endocrine and metabolic disorder associated with reproductive dysfunction, metabolic abnormalities, and reduced quality of life in women of reproductive age. Given the central role of insulin resistance in its pathophysiology, increasing attention has been directed toward insulin-sensitizing therapies, including myo-inositol (MI) and D-chiro-inositol (DCI). Aims The aim of this review was to summarize current evidence regarding the role of MI and DCI in the management of polycystic ovary syndrome (PCOS), with particular emphasis on their mechanisms of action, clinical effectiveness, reproductive outcomes, safety, and limitations of the available evidence. Methods A narrative review of the literature was conducted using the PubMed database. The last search was performed on April 17, 2026. The analysis included 45 publications published between 2011 and 2026, including systematic reviews, meta-analyses, randomized controlled trials, clinical studies, and evidence-based guidelines. Articles were selected according to predefined inclusion and exclusion criteria and were analyzed in thematic sections related to metabolic, reproductive, and safety outcomes. Results The reviewed literature suggests that MI and DCI may improve selected metabolic, hormonal, and reproductive parameters in women with PCOS, including insulin sensitivity, menstrual cycle regularity, and ovulatory function. The combination of MI and DCI in a physiological ratio of 40:1 appears to be the most effective formulation in many clinical settings. Compared with metformin, inositol therapy often shows similar efficacy in selected outcomes, with better tolerability and fewer gastrointestinal side effects. However, the available evidence remains heterogeneous, and some findings are inconsistent, especially regarding long-term outcomes and fertility endpoints. Conclusions MI and DCI represent promising therapeutic options in PCOS management, particularly in women with insulin resistance, menstrual dysfunction, ovulatory disturbances, and selected reproductive outcomes. Nevertheless, the evidence remains heterogeneous, and further high quality studies are needed to clarify their long term effectiveness and precise role in clinical practice.