As many as 5 million U.S. women of reproductive age have polycystic ovarian syndrome or PCOS, a complex metabolic disorder that is a major cause of infertility, according to WomensHealth.gov. Women with PCOS produce many small cysts on their ovaries instead of functioning follicles with healthy eggs.
Symptoms of PCOS may include obesity, male patterns of hair growth called hirsutism, increased acne, irregular cycles and problems with monthly ovulation.
Normalizes Insulin Levels
Metformin is approved by the FDA for the treatment of diabetes because it reduces abnormally high insulin levels, which in turn normalizes levels of circulating glucose, according to Endocrine Online. Although metformin has not been approved by the FDA for PCOS treatment, its off-label use by physicians has been shown to reduce insulin levels in PCOS patients, notes Oxford Journals.
In women with PCOS, high levels of circulating insulin result in hormonal imbalances typically associated with PCOS. Women with PCOS, particularly if they are also obese, often have insulin resistance, which leads to abnormally high levels of insulin in the blood, reports Dr. Vincenzo De Leo and colleagues in their 2003 paper "Insulin-Lowering Agents in the Management of Polycystic Ovary Syndrome," published in volume 24 of "Endocrine Reviews." Metformin treatment effectively relieves PCOS symptoms through its action on insulin.
Restores Ovulatory Function
Metformin treatment was able to restore normal ovulatory cycles in women with PCOS, asserts Dr. J.M. Lord and colleagues, who performed a meta-analysis of 543 women among 13 clinical trials and reported their results in the October 2003 issue of "British Medical Journal."
Obese girls aged 15 to 18 with PCOS noticed a return to normal ovulatory cycles after one month of treatment with metformin, and normal cycles persisted for at least six month after metformin therapy was discontinued, according to Dr. De Leo and colleagues in his paper "Metformin Treatment Is Effective in Obese Teenage Girls With PCOS," published in 2006 in the journal "Human Reproduction."
Improves Body Mass Index
In the same 2006 study, Dr. DeLeo showed that metformin treatment was effective in normalizing the body mass index or BMI of obese teenage girls who had PCOS. The BMIs of girls who received a metformin dose of 1700 mg a day for six months decreased to a normal range between 21 and 24 kg per meter squared.
Metformin treatment is associated with modest decreases in body weight and visceral fat, likely due to its ability to decrease blood levels of androgens and insulin, according to the American Society for Reproductive Medicine. Metformin combined with calorie restriction was most effective in achieving weight loss in obese girls with PCOS.
Normalizes Hormones
Metformin's primary effect is to reduce insulin levels, notes Endojournals.org. Abnormal insulin levels found in women with PCOS stimulate the ovary to produce excess androgens, resulting in abnormally high circulating levels of male hormones.
High androgen levels are responsible for other common symptoms of PCOS including abnormal hair growth and increased acne, reports WomensHealth.gov. Metformin treatment lowered levels of androstenedione and testosterone in women with PCOS, thereby improving acne and hirsutism symptoms.
References
- Endojournals.org: Endocrine Reviews: Insulin-Lowering Agents in the Management of Polycystic Ovary Syndrome, De Vincenzo Leo, et al, 2003
- Oxford Journals: Human Reproduction: Metformin Treatment Is Effective in Obese Teenage Girls with PCOS; De Vincenzo Leo, et al, 2006
- WomensHealth.gov: Polycystic Ovary Syndrome - PCOS
- ASRM: Obesity and Reproduction: An Educational Bulletin
- Endocrine Online: The Use of Metformin in the Polycystic Ovary Syndrome
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