Medications that decrease the amount of glucose produced by the liver

A class of drugs called biguanides has been used for many years in Europe and Canada. In 1994, the FDA approved the use of the biguanide metformin (Glucophage) for the treatment of type 2 diabetes in the U.S. Glucophage is unique in its ability to decrease glucose production by the liver. Briefly, because metformin does not increase insulin levels, when used alone, it does not usually cause hypoglycemia. In addition, metformin has an effect whereby it tends to suppress appetite, which may be beneficial in diabetics who tend to be overweight. Metformin may be used by itself or together with other oral drugs or insulin. It should not be used in patients with kidney impairment and should be used with caution in those with liver impairment. The older biguanides that preceded metformin were associated with a serious condition called lactic acidosis, a dangerous acid build up in the blood resulting from accumulation of the drug and its breakdown products. While metformin is safer in this regard, it is recommended that the drug be discontinued for 24 hours before any procedure involving the intravenous injection of dyes (such as for some x-ray studies of the kidney) or surgery is performed. The dyes may impair kidney function and cause a build up of the drug in the blood. Metformin can be restarted after these procedures once the patient is urinating normally.