Metformin Effects On The Liver

Metformin is a biguanide drug used to treat hyperglycemia in type 2 diabetics. Metformin decreases blood glucose levels by reducing liver production of glucose, decreasing intestinal absorption of glucose and increasing glucose uptake and utilization. The American Diabetes Association recommends metformin as the initial drug therapy for the treatment of type 2 diabetes.

Glucose

The liver, and to a lesser extent the kidney, produces glucose from other molecules and releases it into the bloodstream to be transported to other cells of the body. A study in the journal "Diabetes" reported that liver production of glucose is increased up to 3-fold in type 2 diabetics and metformin treatment reduces it by one-third.

Fat

Nonalcoholic fatty liver disease, or NAFLD, is a disorder in which excessive fat accumulates in the liver. It can progress to cirrhosis and cause liver dysfunction. A study published in the February 2010 issue of the "Journal of Obesity" noted that NAFLD affects between 10 and 30 percent of the world population and is much more prevalent in type 2 diabetics and obese people. This study reported that in obese adolescents with NAFLD, metformin treatment was effective in reducing weight, visceral fat, insulin resistance and insulin levels, all of which are associated with a reduction of NAFLD.

Enzymes

Increases in the enzymes alanine aminotransferase and aspartate aminotransferase in the blood are used clinically as markers to detect decreased liver function and liver injury. People with type 2 diabetes commonly have elevations in the blood concentrations of these enzymes. Metformin treatment decreases these enzyme levels back to baseline.

Toxicity

A few case reports exist that indicate metformin may cause liver toxicity. However, a review of the scientific literature from 1966 to June 2008 published in the "Journal of the American Pharmacists Association" concluded that metformin does not cause liver injury and does not exacerbate pre-existing liver disease or injury.

Lactic Acidosis

Lactic acid is a byproduct of glucose metabolism occurring in the absence of oxygen and is normally cleared by the liver. Lactic acidosis is a condition in which blood and tissue acidity is increased by the accumulation of lactic acid. It is a medical emergency. The National Library of Medicine reported on its website, DailyMed, that the incidence of lactic acidosis in patients taking metformin is exceedingly low, at approximately 0.03 cases per 1000 patient-years. In cases of metformin-induced lactic acidosis, patients had severely compromised kidney function and multiple medical complications.