Metformin and myo-inositol: A comparative analysis

Background In the field of polycystic ovary syndrome, metformin and myo-inositol are frequently employed to treat the endocrine-metabolic aspects of the condition. Accordingly, myo-inositol is sometimes considered as a nutraceutical alternative for metformin. Both compounds have undergone repurposing efforts to identify new applications; however, the mechanisms of both these compounds differ considerably, as does their potential in conditions outside of polycystic ovary syndrome. Objectives This paper discusses contrasts both molecules in terms of mechanism, possible adverse effects, and novel indications, with an aim of detangling the unique properties of each molecule. Methods A narrative review was conducted independently by the authors using the search platforms PubMed, Google Scholar, and Web of Science between August and November 2024. Outcome Myo-inositol has a more acceptable safety profile than metformin, which is known to be associated with gastrointestinal adverse effects and, in rare cases, lactic acidosis. Both myo-inositol and metformin may improve pregnancy outcomes and fertility care; however, the long-term safety of metformin use in pregnancy is unknown. Myo-inositol and metformin have been investigated in the fields of thyroid care, mental health, and cancer, but further research is required to understand their mechanism and potential applications in these disease spaces. Conclusions and Outlook Myo-inositol is a naturally present molecule in physiological conditions, which underlines its importance in a variety of biological functions, as opposed to the strict pharmacological action of metformin. Further study is required to fully understand the potential of each of these molecules, specifically within the fields of mental health and oncology.