Metformin is a generic prescription drug that works to treat type 2 diabetes by helping lower your blood sugar levels. Your response to this drug may vary based on your medical history and diagnosis.

Metformin belongs to a class of medications called biguanides. Metformin is the most common type of biguanide. To learn more about the drug, including details on its uses, side effects, and dosage, see this metformin overview.

Note: Metformin is also available as an oral solution. This article describes the oral tablet form only. If you’d like to learn about metformin’s other forms, talk with your doctor or pharmacist.

The way a drug works is known medically as its mechanism of action.

Metformin treats type 2 diabetes by helping lower blood sugar levels. With type 2 diabetes, your body can’t regulate your blood sugar levels properly.

In someone without diabetes, their body regulates their blood sugar levels by releasing insulin. (Insulin is a hormone that helps your body use sugar as energy.) People with type 2 diabetes may not make enough insulin, or they may have insulin resistance. (With insulin resistance, your body doesn’t respond as well as usual to insulin.) So the hormone doesn’t work properly, which leads to increased blood sugar levels.

Metformin works in the following ways to treat type 2 diabetes:

  • decreases blood sugar made by your liver
  • decreases your body’s absorption of sugar from your food
  • makes your body more sensitive to insulin, so that the hormone works better to decrease your blood sugar level

If you have questions about how metformin works, talk with your doctor or pharmacist.

Note: Your doctor will prescribe metformin along with a balanced diet and an exercise routine. This helps metformin have a better effect on your blood sugar levels.

Metformin oral tablets begin working as soon as you take them. Metformin takes longer to start working than injectable drugs for type 2 diabetes because it’s taken by mouth. So if you need to lower your blood sugar level quickly, your doctor may recommend that you use a fast-acting insulin drug. To learn more, talk with your doctor.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.