What is Metformin?

Physician summary of this common medication used in type II diabetes.

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Diabetes is a widespread disease globally, with an estimated one in every ten individuals in the US affected¹. While lifestyle and dietary factors are considered the first treatment for this condition, medications are prescribed when they are not enough. This article will discuss metformin, which is typically the first agent considered when an individual with diabetes needs extra help.

How does metformin work?

Metformin helps control blood sugar by multiple mechanisms. First, it decreases the production of sugar by the liver, which would help manage blood sugar². It also reduces how much sugar is absorbed from the food you eat². Finally, it makes all your cells more sensitive to the hormone insulin¹. Since type II diabetes can be caused by cells being less sensitive to insulin, leading to higher blood sugars and risk of diabetes complications, this is particularly valuable².

How often do you have to take metformin? How is it taken?

Metformin is a pill, not a shot that you have to administer to yourself. It is generally taken once a day, usually in the evening².

What are the side effects?

Metformin is considered a safe medication and pretty well tolerated². The most common side effects include nausea and diarrhea, sometimes vomiting². It is worth noting that medication side effects tend to be most prominent when starting a medication and usually become less frequent the longer you take it.

Metformin has a black box warning for something called lactic acidosis, which rarely occurs when taking the medication². If you imagine 30,000 people packed into a football stadium, 29,999 of these people taking metformin would not have this complication². Factors that contribute to this complication are classically people with greatly diminished kidney function. Doctors are aware of this complication. If there is any concern that this could happen, such as when someone is hospitalized due to a short-term significant kidney function impairment, the medication is typically stopped until it would be safe to administer.

Will I have to poke my finger every day to check my blood sugar?

Compared to insulin, which is injected, metformin does not require daily blood sugar checks¹. If one’s diabetes has progressed and your doctor recommends it, it could be a good thing to do. Generally, your blood sugar would be checked at routine visits every three to six months¹.


Metformin is a widely prescribed medication to supplement diabetes treatment. It is generally well-tolerated and taken once a day. It generally does not require daily blood sugar checks.


  1. https://www.cdc.gov/diabetes/library/features/diabetes-stat-report.html
  2. https://www.ncbi.nlm.nih.gov/books/NBK518983/


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Medika Columnist

M.D. trained in the US, now researching SARS-CoV-2 and COVID-19 in Canada for his Ph.D. After earning my Ph.D., I will be pursuing an Anatomic Pathology residency embracing my path towards being a physician-scientist. My academic interests are directed towards topics that provide the greatest net benefit for the greatest number of people. I love complicated, messy, and poorly understood topics.

I enjoy writing in my spare time, along with 3D printing and staying connected with my family. I have been a longstanding proponent for global health with projects ranging from supporting Doctors without Borders (MSF) to Syrian refugees (Syrian American Medical Society).



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