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Metformin: Myths vs. Facts

Chances are, if you have type 2 diabetes, you have at some point been prescribed metformin. This medication has a long history. It was first used for diabetes management in the 1950s outside the United States, but then it was approved by the US Food and Drug Administration (FDA) for use in the United States in the 1990s.1,2

It's estimated that 150 million people are prescribed metformin each year.3

Despite its long track record, I still hear many myths about metformin in my work as a Certified Diabetes Care and Education Specialist (CDCES). My hope is this article can help you understand the facts about metformin and type 2 diabetes.

Myth: Metformin causes kidney damage

This is one of the MOST common concerns I hear about metformin. Metformin is eliminated through your kidneys, just like many other medicines. And, just like other medicines, if your kidneys aren't working well, metformin doses need to be adjusted or stopped.

Past concerns were that metformin could cause a severe condition called lactic acidosis if not cleared from the body. However, studies and observational data show that metformin does not increase the risk of lactic acidosis more than other diabetes medicines. For that reason, in 2016 the FDA loosened its guidelines on metformin use for those with chronic kidney disease (CKD).3,4

Metformin does not cause kidney damage, but some studies suggest it lowers the risk of end-stage renal disease.3

Myth: There are no ways to help reduce side effects

Nausea, bloating, and diarrhea are some of metformin's most common side effects. However, some tips can help reduce the severity of side effects:3

  • Starting on a low dose and slowly increasing doses over time
  • Use extended-release vs. regular metformin
  • Take metformin with meals

Generally, over time, these side effects improve. For those that don't see improvement, it may not be the right fit.3

Myth: Metformin is used only for type 2 diabetes

Metformin is FDA-approved to treat type 2 diabetes. However, it is used off-label to manage other health conditions, particularly ones with high insulin resistance, such as polycystic ovarian syndrome (PCOS), prediabetes, and gestational diabetes.

Use in type 1 diabetes and those with non-alcoholic fatty liver disease (NAFLD) also takes place.  Interestingly, metformin is also showing promise in cancer treatments and cancer prevention.3

Myth: Metformin doesn't have any protective impacts on other health risks

Metformin may protect your heart – and your life. Multiple studies have reviewed metformin's protective impact on heart-related events (such as heart attacks, heart failure, cardiovascular disease, angina, and heart arrhythmia).

In fact, some studies showed that metformin users had a lower risk of death than people without diabetes. One study showed that people with type 2 diabetes and chronic kidney disease had a 51 percent lower risk of death and heart-related deaths with metformin use. In a 2019 review of 40 clinical trials and more than 1 million patients, metformin was linked to lower heart events like those listed above, lower risk of death, and lower risk of heart-related deaths.3

Myth: Metformin can't cause vitamin imbalances

Long-term use of metformin can cause low levels of vitamin B12. This depends on many factors, including how long someone takes metformin, their dose, their age, and so on.3

Low levels of B12 can cause anemia (low red blood cells) or peripheral neuropathy.3

Because peripheral neuropathy can also be a diabetes complication, other causes, such as low vitamin B12 levels, can easily be overlooked. The American Diabetes Association recommends monitoring B12 levels for those taking metformin, especially with anemia or peripheral neuropathy. Vitamin B12 supplements may be needed.5

Ask your doctor or pharmacist if you have questions about metformin or your type 2 diabetes treatment plan.

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