Impaired Prolactin-Lowering Effects of Metformin in Women with Polycystic Ovary Syndrome

The study involved 50 prediabetic women with hyperprolactinemia, half of whom had Polycystic Ovary Syndrome (PCOS). It found that metformin, a drug used to treat diabetes, had different effects on women with PCOS compared to those without. In women without PCOS, metformin reduced levels of prolactin, a hormone that can cause menstrual irregularities. However, in women with PCOS, metformin did not have the same effect on prolactin levels. Instead, it reduced levels of luteinizing hormone (LH), testosterone, and free androgen index (FAI), which are typically elevated in PCOS. The study suggests that the presence of PCOS may reduce the impact of metformin on lactotrope secretory function, which is responsible for prolactin production, due to increased testosterone production. The study also found that metformin improved insulin sensitivity in both groups, but the effect was less pronounced in women with PCOS.