Metformin

Metformin (INN; trade names Glucophage, Riomet, Fortamet, Glumetza, Obimet, Dianben, Diabex, Diaformin, and others) (pronounced /mɛtˈfɔrmɪn/) is an oral anti-diabetic drug from the biguanide class. It is the first-line drug for the treatment of type 2 diabetes, particularly in overweight and obese people and those with normal kidney function,[1][2][3] and evidence suggests it may be the best choice for people with heart failure.[4] It is also used in the treatment of polycystic ovary syndrome.

Metformin is the most popular anti-diabetic drug in the United States and one of the most prescribed drugs in the country overall, with more than 40 million prescriptions filled in 2008 for generic metformin alone.[5] When prescribed appropriately, metformin causes few adverse effects—the most common is gastrointestinal upset—and, unlike many other anti-diabetic drugs, does not cause hypoglycemia if used alone. It also helps reduce LDL cholesterol and triglyceride levels, and may aid weight loss. As of 2009, metformin is one of only two oral anti-diabetics in the World Health Organization Model List of Essential Medicines (the other being glibenclamide).[6]

Indications

The main use for metformin is in the treatment of diabetes mellitus type 2, especially when this accompanies obesity and insulin resistance. Metformin is the only anti-diabetic drug that has been proven to protect against the cardiovascular complications of diabetes.[11] This was first shown in the United Kingdom Prospective Diabetes Study, a large study of overweight patients with diabetes.[12] Unlike the other most-commonly prescribed class of oral diabetes drugs, the sulfonylureas, metformin (taken alone) does not induce hypoglycemia.[13] Hypoglycemia during intense exercise has been documented, but is extremely rare.[14] It also does not cause weight gain, and may indeed produce minor weight loss.[15] Metformin also modestly reduces LDL and triglyceride levels.[16]

It is also being used increasingly in polycystic ovary syndrome (PCOS),[17] non-alcoholic fatty liver disease (NAFLD)[18] and premature puberty,[19] three other diseases that feature insulin resistance; these indications are still considered experimental. Although metformin is not licensed for use in PCOS, the United Kingdom's National Institute for Health and Clinical Excellence recommends that women with PCOS and a body mass index above 25 be given metformin when other therapy has failed to produce results.[20] The benefit of metformin in NAFLD has not been extensively studied and may be only temporary.[21]

It may reduce weight gain in patients taking atypical antipsychotics.[22]