Effects of short-term and long-term metformin treatment on menstrual cyclicity in women with polycystic ovary syndrome.

The purpose of this retrospective study was to compare the frequency of menstrual cyclicity between two groups of patients with polycystic ovary syndrome: women who were followed while on metformin for 3-6 months and those who were followed for >6 months. The results showed that metformin is highly effective in normalizing menstrual cyclicity in women with polycystic ovary syndrome (the overall response rate was 69%, with 88% of responders achieving normal cyclicity), especially with a treatment duration of 6 months or longer (the response rate was 40% higher for women who were treated with metformin for >6 months vs. 3-6 months, 77% vs. 55%).