Metformin is an antidiabetic agent used to lower glucose (blood sugar) levels. Traditionally, it has been used to treat people with type 2 diabetes, which occurs when glucose accumulates in the blood due to the body’s inability to effectively use insulin (a hormone that regulates glucose). Research is under way to determine the effect of metformin in treating symptoms related to polycystic ovarian syndrome (PCOS). This is a type of endocrine system disorder in which the ovaries produce excessive amounts of androgens (male hormones such as testosterone). Some patients with PCOS are also insulin resistant.

Metformin belongs to a class of drugs called biguanides. These drugs prevent the liver from producing too much glucose, and reduce the amount of glucose from dietary sources. They also increase the sensitivity of muscle tissue to insulin, which allows for better absorption of glucose. Biguanides slow the absorption of glucose from food digested in the small intestine.

Metformin is the only biguanide approved by the U.S. Food and Drug Administration (FDA) for the treatment of type 2 diabetes. However, clinical trials are testing the use of metformin in treating PCOS. “Off-label” use of metformin is currently prescribed by some physicians for PCOS patients. Off-label use allows physicians to prescribe FDA-approved drugs for patients who may benefit from their use, even though the drug has not been specifically approved for treating their condition.

Among other symptoms, PCOS causes irregular menstrual cycles and raises the risk of heart disease. Clinical trials have found that among women with PCOS, metformin:

• Reduces androgen levels. High levels of male hormones are a major contributor to PCOS.
  
  
• Reduces insulin resistance. High insulin levels may contribute to high androgen levels and irregular ovulation in women with PCOS.
  
  
• Improves ovulation. Metformin helps women resume their  regular menstrual cycles. Research indicates that the drug improves ovulation in normal-weight and overweight patients and increases fertility in some women.
  
  
• Controls hirsutism when prescribed at higher doses. Hirsutism is excessive hair growth throughout the face and body. It is a symptom commonly associated with PCOS because of the high male hormone levels.
  
  
• Helps reduce the incidence of PCOS-associated obesity.

Researchers believe that regular use of metformin may ultimately help reduce cardiovascular disease complications that stem from PCOS. Metformin may be a particularly good treatment option for women diagnosed with both PCOS and type 2 diabetes. However, to date, the FDA has not specifically approved metformin for treating PCOS. Metformin may help increase fertility among some women with PCOS. However, recent studies show that although metformin treats other symptoms of PCOS well, other drugs, such as the fertility drug clomiphene, work better for women who are trying to get pregnant.

Metformin is sold in various formulations and under several brand names, such as: