Metformin is an antidiabetic agent that belongs to a class of drugs called biguanides. The U.S. Food and Drug Administration (FDA) has approved metformin for use in treating type 2 diabetes, which occurs when glucose (blood sugar) builds up in the blood due to the body’s inability to effectively use insulin (a hormone that regulates glucose). Researchers are also studying metformin as a possible treatment for symptoms associated with polycystic ovarian syndrome (PCOS). Some physicians prescribe metformin to treat irregular ovulation for women with PCOS.

PCOS is a disorder of the endocrine system in which a woman's ovaries produce excessive amounts of androgens (male hormones such as testosterone). Among other symptoms, PCOS causes irregular menstrual cycles and raises the risk of heart disease. Clinical trials have found that metformin:

• Reduces androgen levels. High levels of male hormones significantly contribute to PCOS.
  
  
• Improves ovulation. Metformin allows women to resume regular menstrual cycles and can increase 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.
  
  
• Helps reduce the incidence of PCOS-associated obesity. It can also lead to better glucose regulation through its effects on insulin resistance. 

To date, the FDA has not specifically approved metformin as a treatment for PCOS. However, clinical trials are under way that may eventually result in the FDA approving metformin for PCOS therapy.