Metformin has been used for decades and remains one of the most widely prescribed medicines for type 2 diabetes. It lowers blood sugar mainly by reducing the amount of glucose released by the liver and helping the body use insulin more effectively.
Type 2 diabetes develops when the body does not respond properly to insulin or cannot make enough of it to keep blood sugar under control. Over time, high blood sugar can damage blood vessels, nerves, kidneys and other organs, and it greatly increases the risk of heart disease and stroke.
Metformin has attracted attention because its benefits may extend beyond blood sugar control. One of the best-known sources of evidence is the UK Prospective Diabetes Study, or UKPDS, a large long-term study of people with newly diagnosed type 2 diabetes.
In a major UKPDS report published in The Lancet in 1998, overweight patients assigned to intensive blood sugar control with metformin had a 39% lower risk of heart attack than patients mainly treated with diet alone. The study also reported reductions in several other diabetes-related outcomes and helped establish metformin as an important treatment.
Metformin may also have a modest effect on body weight. Unlike some diabetes medicines that can cause weight gain, metformin is generally weight-neutral or may lead to a small amount of weight loss in some people.
Researchers are also studying whether metformin affects inflammation and other processes linked to aging, cancer and cardiovascular disease. These possible benefits are interesting, but many remain under investigation, and metformin should not be viewed as a proven treatment for conditions it has not been approved to treat.
Like any medicine, metformin can cause side effects. The most common problems involve the digestive system, including diarrhea, nausea, stomach discomfort and loss of appetite, especially when treatment first begins.
Starting with a lower dose and slowly increasing it can make these symptoms easier to manage. Taking metformin with meals can also help, and some people tolerate extended-release versions better than standard tablets.
Long-term metformin use can reduce the body’s ability to absorb vitamin B12. Low B12 can eventually contribute to anemia, tiredness, numbness, tingling or other nerve problems, so doctors may recommend testing in people who have symptoms or other risk factors.
A much rarer complication is metformin-associated lactic acidosis, in which lactic acid builds up to dangerous levels in the blood. The risk is very low when metformin is prescribed appropriately, but it becomes more important when a person has severe kidney problems or certain serious illnesses that reduce oxygen supply or affect the body’s ability to clear the medicine.
Metformin by itself usually does not cause dangerously low blood sugar because it does not directly force the pancreas to release more insulin. However, low blood sugar can occur when it is combined with medicines such as insulin or sulfonylureas, particularly if a person misses meals or has other risk factors.
For most suitable patients, metformin has a long safety record and remains an effective and inexpensive way to manage type 2 diabetes. Doctors may check kidney function and other health measures over time to make sure it continues to be appropriate.
Metformin is not the best choice for every person, and modern diabetes treatment has expanded considerably. Depending on a patient’s heart health, kidney health, weight and other needs, doctors may use metformin alone or combine it with newer medicines that provide additional benefits.
Overall, metformin remains an important tool for controlling type 2 diabetes, with possible advantages for weight and cardiovascular health. Its benefits are strongest when the medicine is used as prescribed and combined with regular medical care, healthy eating and physical activity.
If you care about diabetes, please read studies about diabetes and vitamin B12, and the right diet for people with type 2 diabetes.
For more health information, please see recent studies about how to eat smart with diabetes, and turmeric and vitamin D: a duo for blood pressure control in diabetic patients.
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