Polycystic ovary syndrome (PCOS) is a common and heterogeneous disorder of women in reproductive age. It is characterized by hyperandrogenism and chronic anovulation. Several studies in diverse populations estimate it's prevalence at 5-10%. Women present, in a high percentage of cases, with obesity, hirsutism, acne, menstrual irregularities and infertility. Although the exact physiopathology of PCOS remains unknown, several studies tend to point to insulinoresistance (IR) as the cause of the syndrome. IR is present in 60 to 70% of patients independently of obesity. Compensatory hyperinsulinism has a pivotal role in the physiopathogenesis of PCOS. In vitro, insulin stimulates androgen synthesis in thecal cells and decrease sex hormone-binding globulin synthesis in the liver, increasing free androgen availability.
Due to the high prevalence of IR, PCOS shares components of metabolic syndrome: abdominal obesity, impaired glucose tolerance, gestational and type 2 diabetes, abnormalities in lipid profile, blood hypertension, endothelial dysfunction and probably cardiovascular disease.
In the past, PCOS treatment was focus on ovulation induction for infertility, oral contraceptives for irregular bleeding, and androgens antagonists for hirsutism or acne. In later years insulin sensitizing agents have been used to reduce hyperinsulinemia, improve ovary function and associated metabolic abnormalities. Metformin (MTF), a biguanide, usually used in obese patients with type 2 diabetes,inhibits glucose hepatic production,decreases insulin secretion and increases peripheral insulin sensitivity.
Some studies have reported an improvement in insulin sensitivity associated with reduction of hyperandrogenism and improvements in reproductive abnormalities with MTF. On the other hand, other authors failed to observe those changes. However, an off label indication for it usage in PCOS for FDA and the lack of large controlled trials, MTF indication to treat PCOS has grown dramatically in later years.
In obese women with PCOS, weight loss effectively ameliorates hyperandrogenism and metabolic disorders by improving insulin resistance.
Some trials have suggested that those effects could be improved with insulin sensitizing agents without changes in body weigh.
The present study was designed to assess, in a randomized, double-blind, placebo-controlled way, the effects of MTF in addition to lifestyle modifications on endocrine and metabolic disturbances in women with PCOS.