All About Metformin As a Treatment for PCOS

This blog post is written by Olesya (Oleska) Prokopovych, a nutrition student volunteering at Nourish & Nurture

The first time I heard of Metformin was when learning about the treatments for type 2 diabetes! I then learned it is also used in PCOS treatment. The common factor between both conditions is insulin resistance, which Metformin helps with! Insulin resistance affects people with PCOS two to three times more than the general population. Up to 70% of individuals with PCOS experience insulin resistance. Although taking metformin can be helpful to some people with PCOS, it is not used for all. So, if you are someone with PCOS who is taking metformin and is not sure why or what it does for your body, read on. This blog post discusses the connection between the syndrome and insulin resistance and how metformin can be used as a treatment.

What is insulin resistance?

Although not a diagnostic criterion for PCOS, insulin resistance is a common feature of it. Let us take a few steps back and address the elephant (or hormone) in the room. Insulin is a hormone that is produced in the body and works to regulate glucose levels in the blood. After we eat a meal—especially one that contains carbohydrates—our bodies break down the food into glucose units that can be used to produce energy in the body. Insulin’s job is to take the high levels of glucose in the blood and escort them to different parts of the body for energy and storage, like in our muscles and liver. With insulin resistance, the hormone has a difficult time delivering and storing away that glucose. As a result, the pancreas realizes that blood glucose levels are still high so it releases more and more insulin, which leads to high insulin in the blood or what’s called hyper-insulin-emia. Abnormally high levels of insulin in the body may result in inflammation, cravings, and weight gain.

Insulin resistance is a major physiological driver of PCOS. High insulin levels cause the ovaries to produce excess testosterone. This results in an imbalance of hormones, and in turn, impairment of normal menstruation and ovulation. It could also cause some unpleasant symptoms and manifestations such as skin tags and dark velvety patches on the skin.

What is metformin (Glucophage)?

Metformin is an oral drug marketed under the name Glucophage and is very well known as a treatment for type 2 diabetes for insulin sensitization. It is one of the most common treatment recommendations for PCOS insulin resistance to improve insulin sensitivity. Remember when I mentioned that insulin resistance involves insulin not being able to deliver and store glucose properly into the cells? Well, metformin helps with that. This drug serves three of the following main functions in the body:

1. Decrease hepatic (liver) glucose production

Normally, when the body has an excess amount of glucose, it gets turned into something called glycogen and stored in the liver. Then, when the body needs that energy, glycogen is broken down into glucose. As mentioned previously, insulin resistance involves the inability to store blood glucose properly. Metformin decreases the liver’s ability to produce unnecessary amounts of glucose.

2. Decrease intestinal absorption of glucose

When you are digesting your food, your intestines are working hard to absorb all the nutrients and other good things. Unfortunately, with insulin resistance, there is already too much glucose in the bloodstream. Metformin decreased the intestines’ ability to absorb glucose any further. This excess glucose is then released into your stool, sometimes causing diarrhoea.

3. Improve insulin sensitivity

Metformin allows insulin to take glucose to all the right places in the body and keep blood glucose levels in a healthy range. Instead of staying in the blood, insulin then helps glucose get transported to the parts of the body that need to convert glucose into energy. Otherwise, glucose gets stored to be used later on.

Metformin dosing

A typical dose of metformin for PCOS would be 500 mg per day for one to two weeks. It is recommended to take this dose with your main meal to lessen side effects and develop tolerance to the drug. Generally, the dose can be increased weekly or bi-weekly by 500 mg per day until a maximum dose of 2500 to 2550 mg/day is achieved.

Side effects of Metformin

Like any medication, metformin has side effects. Some side effects might only occur when you just start taking this medication. Commonly, these include gastrointestinal issues such as diarrhea, nausea, and upset stomach. Luckily, these kinds of symptoms can be reduced if taking metformin with meals and with time. More rarely, you may experience a metallic taste when starting the medication, or hypoglycemia (low blood sugar).

A more serious side effect is lactic acidosis. Although very rare, this condition may be fatal if not treated appropriately. Some signs to watch out for include:

  • Cold hand or feet

  • Feeling dizzy or lightheaded

  • Slow or irregular heartbeat

  • Feeling weak or tired

  • Unusual muscle pain

  • Trouble breathing

  • Feeling sleepy or drowsy

  • Stomach pains, nausea, or vomiting

If you are taking metformin and you are experiencing any of these symptoms, please contact your health care practitioner immediately.

Drug-nutrient interactions

Sometimes medications act differently when taken with certain nutrients such as vitamins, minerals, and foods/beverages. Metformin is known to reduce the body’s ability to absorb vitamin B12 and sometimes folic acid. Vitamin B12 does many important things for the body including making sure our body’s nerve and blood cells are healthy. As well, B12 helps make DNA, the genetic material in our cells. Folic acid is also a B vitamin that is used to produce DNA. It is important to mention that drinking alcohol has a major interaction with metformin. Doing so may increase the risk of lactic acidosis.

Final Remarks

Metformin is an insulin sensitizer, which as a result, could reduce many of the symptoms of PCOS. It could induce ovulation and menstruation and help prevent gestational diabetes. I hope this post has been insightful and helpful in clearing up some confusion. If you have any concerns or questions about metformin, please speak to your health care practitioner.


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Olesya (Oleska) is a 5th year student in the Nutrition and Food program at Ryerson University. Last year she realized she wishes to become a Registered Dietitian and has since been doing everything she can to gain experience and prepare herself for grad school applications in the near future. She has always loved food and cared very deeply for her health and well-being.

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