Physicians commonly prescribe Metformin if you have Type 2 diabetes and need help controlling your blood sugar. It reduces how much glucose you absorb from food and the amount your liver produces. On rare occasions, however, Metformin causes liver dysfunction and a serious metabolic condition involving the liver. For this reason, physicians exercise caution when prescribing Metformin to patients with liver disease.
In healthy individuals, the liver produces glucose to keep blood sugar stable when you haven't eaten for several hours. Uncontrolled glucose production in the liver may cause high blood sugar in individuals with Type 2 diabetes. Researchers discovered that Metformin blocks critical enzymes involved in signaling the liver to produce glucose, thereby decreasing blood sugar levels. Their work was reported in the February 2013 edition of the journal "Nature."
Lactic Acid Production
Your muscles, brain, skin and other tissues produce a substance called lactic acid. Under normal circumstances, your liver and kidneys remove lactic acid from the blood and convert some of it to glucose. If a life-threatening metabolic condition known as lactic acidosis occurs, lactic acid levels increase faster than the liver can keep up with. Though its mechanism is unclear, Metformin causes lactic acidosis in a small segment -- up to 1 percent -- of patients, according to NYU Langone Medical Center. Almost all reported cases occurred in patients with underlying metabolic issues, such as liver or kidney disease.
Mild Liver Dysfunction
According to LiverTox, a publication of the U.S. National Library of Science drug database, Metformin may occasionally cause mild liver toxicity, characterized by minor elevations in liver enzymes. It occurs in less than 1 percent of the patients taking Metformin and usually appears within the first one to eight weeks of treatment, according to LiverTox. Liver problems usually resolve quickly once you stop taking the Metformin, according to LiverTox.
Knowing the Signs
Your liver is a critical organ that is responsible for detoxifying your blood. While Metformin influences the liver in some positive ways that result in decreased glucose output, it's capable, under rare circumstances, of negatively affecting liver function. Seek immediate medical attention if you notice signs of liver toxicity, which include weakness, fatigue or jaundice.