Pituitary Effects of Metformin in Men With Early-Onset Androgenic Alopecia

Males with early-onset androgenic alopecia are characterized by elevated androgen levels. The aim of the present study was to investigate whether the presence of this condition modulates the impact of metformin on pituitary hormone production. This study compared 2 groups of young men with prediabetes, matched for age, blood pressure, and insulin sensitivity: 23 subjects with early-onset male-pattern baldness (group 1) and 25 individuals with normal hair growth (group 2). Throughout the study, both groups were treated with metformin for 6 months. Circulating levels of glucose, insulin, glycated hemoglobin, gonadotropins, thyrotropin, prolactin, adrenocorticotropic hormone, insulin-like growth factor-1 and androgens were determined at the beginning of the study and 6 months later. At entry, luteinizing hormone (LH), the LH/follicle-stimulating hormone ratio, total testosterone, bioavailable testosterone, adrenocorticotropic hormone and dehydroepiandrosterone sulfate were higher in group 1 than in group 2. The effect of metformin on fasting glucose, insulin sensitivity, and glycated hemoglobin was more pronounced in group 2 than in group 1. Only in group 1, metformin reduced LH levels and the LH/follicle-stimulating hormone ratio. Metformin did not affect plasma levels of the remaining hormones. In untreated men with androgenic alopecia (group 3, n = 22), glucose homeostasis markers and hormone levels remained similar throughout the study period. The obtained results suggest that the impact of metformin on gonadotroph secretory function is stronger in men with early-onset androgenic alopecia than in men with normal hair growth. Metformin treatment may protect men with early-onset androgenic alopecia against the development of gonadotroph hyperplasia and/or focal testicular changes.