What Is Metformin?

Metformin is a prescription medication used to treat type 2 diabetes. The medicine is available as an oral solution and tablet. Some patients may be able to take it as an extended-release tablet. Individuals who take the immediate-release oral tablet are typically started on an initial dose of 850 to one thousand milligrams per day. Doctors generally increase the patient's dose by five hundred milligrams each week until the maintenance dose (long-term daily dose) is reached. For most patients, the recommended maintenance dose is two thousand milligrams, and it is safe to take a maximum of 2,550 milligrams per day. If the extended-release tablet is prescribed, the initial dose is between five hundred to one thousand milligrams each day, and the maximum daily dose is two thousand milligrams. This medication is not recommended for individuals with impaired liver function, and elderly patients may be prescribed less than the maximum recommended dose.

The uses, side effects, precautions, and medication interactions associated with metformin are discussed below.

How It Works


Metformin belongs to a group of medicines known as biguanides. These medicines were originally derived from French lilacs, and they were first introduced in the United States in the 1950s. Proguanil and chlorproguanil are both biguanides, and they are used to treat malaria. Metformin controls the level of glucose in a patient's blood by decreasing the amount of glucose absorbed from food and beverages. It reduces the amount of glucose the liver manufactures and helps the body become more sensitive to insulin (a hormone that regulates blood glucose). However, metformin does not affect the amount of insulin the body produces. Patients who have been diagnosed with type 2 diabetes will usually be offered metformin as the first treatment option. It may need to be used in combination with other medicines to achieve optimal blood glucose control.

Learn about the uses and benefits of metformin next.

Emily Fowler