Abstract
Background Metformin was found to decrease serum levels of prolactin and thyrotropin. The aim
of this study was to investigate the effect of this drug on hypothalamic-pituitary-ovarian
axis activity in postmenopausal women with recently diagnosed and untreated glucose
metabolism abnormalities.
Methods The study included three matched groups of postmenopausal women: patients with type
2 diabetes (group A, n=16), women with prediabetes (group B, n=14), and individuals
with normal glucose metabolism (group C, n=14). Women with diabetes were then treated
with high-dose metformin (3 g daily), while women with prediabetes received moderate
doses of this agent (1.7 g daily). Glucose homeostasis markers, as well as serum levels
of FSH, LH, thyrotropin, prolactin, estradiol and creatinine were measured at baseline
and after 16 weeks of metformin treatment.
Results In both groups of metformin-treated women, the drug improved glucose homeostasis.
High-dose metformin treatment reduced circulating levels of FSH and tended to reduce
serum levels of LH, and these effects correlated with an improvement in insulin sensitivity.
No changes in gonadotropin levels were observed in prediabetic women receiving moderate
doses of metformin. Serum levels of thyrotropin, prolactin and estradiol, as well
as the estimated glomerular filtration rate remained at a similar level throughout
the study.
Conclusions Our study shows that the effect of metformin on hypothalamic-pituitary-ovarian axis
activity in postmenopausal women depends on its dose and the magnitude of insulin
resistance.
Key words
FSH - LH - menopause - metformin
