Should You Consider Taking A Vitamin B12 Supplement With Metformin?

Vitamin B12 is able to be obtained through our diet and can be found in dairy, meat, and fish, reports WebMD

This small-but-mighty essential nutrient bears quite a bit of responsibility. It aids in DNA production while also supporting the health of our brain, nervous system, and red blood cells. 

Those who do not receive enough vitamin B12 in their system may be at risk for certain health issues. According to Healthline, symptoms of vitamin B12 deficiency include diarrhea, exhaustion, pale skin, loss of appetite, constipation, and bleeding gums, among others. Ultimately, patients may experience brain function decline, permanent nerve damage, memory loss, and more.

Metformin, a prescription medication widely used to treat those with type 2 diabetes, has been found to potentially reduce the body's ability to absorb vitamin B12, reports GoodRx Health. In some cases, this may increase a patient's risk for vitamin B12 deficiency. 

While this problem was first detected in the late '60s, research over the years has yielded mixed results when it comes to the degree to which metformin may influence vitamin B12 deficiency in patients with diabetes. A 2019 study published in Medicine found that over 22% of patients taking metformin for six months or more developed serum vitamin B12 deficiency. However, GoodRx Health notes that some research indicates prevalence rates may be as high as 50%.

Should all metformin patients take a B12 supplement?

Does this mean that all metformin patients should automatically be taking a B12 supplement? GoodRx Health says this is not the case. Rather, patients with diabetes taking metformin should only do so if instructed by their physician, as they can help you further determine the proper dosage amount, as well as what form of supplementation would be best. For example, vitamin B12 injections may be more effective for those with severe malabsorption-related deficiencies. Generally speaking, patients with diabetes who take metformin should have their B12 levels continuously monitored by their doctor on an annual basis.

It's important to note that not all patients who take metformin will develop a B12 vitamin deficiency. "In my office, patients on metformin who are B12 deficient isn't something we see often," Dr. Caroline Messer, an endocrinologist specializing in bone loss at Lenox Hill Hospital in New York, explained to Healthline.

However, because vitamin B12 deficiency can place a patient at an increased risk for nerve damage, patients with diabetes who are prescribed metformin and display low levels of vitamin B12 may benefit from taking a supplement to help prevent any additional or future damage (via Healthline). This way, patients are able to treat the deficiency without having to forgo their diabetes treatment.