They work by reducing the production of glucose that occurs during digestion.
Metformin is the only biguanide currently available in most countries for treatingdiabetes.
Metformin is sold under the brand names Fortamet and Glumetza, and also as a generic medication.
Francis Dean / Getty Images
It is also available in combination with several other types of diabetes medications, such assulfonylureas.
Metformin works by controlling the amount of sugar in your blood.
It does not affect how much insulin your body produces, but it increases sensitivity toinsulin.
Buformin was developed in Germany in 1957 but was never sold in the United States.
It also was found to cause an increased risk of lactic acidosis.
These forms of biguanides may still be available in some countries.
Other types of biguanides, called proguanil and chlorproguanil, are used as antimalarial drugs.
It is also being investigated for potential cancer-fighting and cardioprotective benefits.
If you experience any of these symptoms, seek immediate medical attention.
The FDA previously identified unacceptable levels of N-Nitrosodimethylamine (NDMA) in certain lots.
Stopping metformin without a replacement can pose serious health risks to those with key in 2 diabetes.
Dosage
Metformin is taken at doses of 500 milligrams (mg) to 2550 mg a day.
Depending on the form, it is taken once to three times daily.
Instructions must be followed for the safe use of each product.
It can safely be stored at room temperature.
Metformin should be taken with meals to prevent side effects.
If you forget a dose, take your next dose at the usual time rather than double up.
Side Effects
Metformin does not cause excessivehypoglycemia, which is an advantage over some other diabetes medications.
It also doesnt cause weight gain, and it has benefits for some cardiovascular risk factors.
It may even help with weight loss and loweringcholesterol.
It should always be taken with food to reduce the risk of gastrointestinal issues.
Over time, metformin may blockvitamin B12absorption in the body.
Ask your healthcare provider whether B12 vitamin supplements are right for you.
The risk is very lowaround one in 30,000 people taking metforminbut the condition can be fatal.
Report any changes or unusual symptoms to your healthcare provider right away when youre combining metformin with other medications.
American Diabetes Association Professional Practice Committee.9.
Pharmacologic Approaches to Glycemic Treatment: Standards of Care in Diabetes2025.Diabetes Care.
2025;48(Supplement_1):S181-S206.
doi:10.2337/dc25-S009
National Library of Medicine: MedlinePlus.Metformin.
Bailey CJ.Metformin: historical overview.Diabetologia.
Food and Drug Administration.FDA alerts patients and health care professionals to nitrosamine impurity findings in certain metformin extended-release products.
