Metformin, marketed under the trade name Glucophage among others, is the first-line medication for the treatment of type 2 diabetes, particularly in people who are overweight. It is also used in the treatment of polycystic ovary syndrome. It is not associated with weight gain. It is taken by mouth.
Metformin is generally well tolerated. Common side effects include diarrhea, nausea, and abdominal pain. It has a low risk of causing low blood sugar. High blood lactic acid level is a concern if the medication is prescribed inappropriately or in overly large doses. It should not be used in those with significant liver disease or kidney problems. While no clear harm comes from use during pregnancy, insulin is generally preferred for gestational diabetes. Metformin is a biguanide antihyperglycemic agent. It works by decreasing glucose production by the liver and increasing the insulin sensitivity of body tissues.
Metformin was discovered in 1922. French physician Jean Sterne began study in humans in the 1950s. It was introduced as a medication in France in 1957 and the United States in 1995. Metformin is on the World Health Organization's List of Essential Medicines, which lists the most effective and safe medicines needed in a health system. Metformin is the most widely used medication for diabetes taken by mouth. It is available as a generic medication. The wholesale price in the developed world was between US$0.21 and $5.55 per month as of 2014. In the United States, it costs US$5 to US$25 per month. In 2016, it was the fourth-most prescribed medication in the United States, with more than 81 million prescriptions.