Nickan Research Institute Journal of Parathyroid Disease 2345-6558 8 1 2020 01 01 Metformin and thyroid; a narrative review to current concepts e11168 e11168 EN Zeinab Rezvani Hamid Nasri https://orcid.org/0000-0003-1673-5741 Journal Article 2020 07 14 2020 10 07 Metformin has different metabolic effects on diverse tissues through various pathways such as hypothalamic-pituitary-thyroid axis. It is shown that metformin influence on thyroid structure considerably and reduced nodule volume by 30-50% of the first volume in diabetic patients. Besides, metformin shows anti-mitogenic and proapoptotic properties in thyroid cancer cells and enhances the antitumor effect of chemotherapeutic drugs. It prevents cancer growth by reduction of hyperinsulinemia too.