"Metformin, marketed under the brand name Glucophage among others, is that the first-line medication for the treatment of type 2 diabetes, particularly in people that 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 adverse effects include diarrhea, nausea, and abdominal pain. It has a coffee risk of causing low blood glucose. High blood lactic acid level is a concern if the medication is used in overly large doses or prescribed in persons with severe kidney problems. It is not recommended in those with significant disease. While no clear harm comes from use during pregnancy, insulin is usually preferred for gestational diabetes. Metformin is a biguanide antihyperglycemic agent. It works by decreasing glucose production by the liver, by increasing the insulin sensitivity of body tissues, and by exerting an anorexiant effect, thereby reducing caloric intake."