Metformin and PCOS

Prescription for metformin for PCOS

If you have Polycystic ovary syndrome (PCOS), chances are your doctor has discussed the use of metformin to help you. Metformin is a common and well-studied medication for use in individuals with type 2 diabetes. Other names for metformin include glucophage, glucophage XR, glumetza, and fortamet. Metformin works as an insulin-sensitizer to reduce your body’s production of glucose. It is believed that approximately 70% of women with PCOS have insulin resistance.

If not treated, people with insulin resistance can develop type 2 diabetes.

How Does Metformin Work?

Metformin lowers blood glucose and insulin levels in three ways:

  1. It suppresses the liver's production of glucose.
  2. It increases the sensitivity of your liver, muscle, fat, and cells to the insulin your body makes.
  3. It decreases the absorption of carbohydrates you consume.

Other added benefits associated with metformin use in women with PCOS include improved ovulation and cholesterol levels and hirsutism symptoms like acne and excess hair growth. Metformin is sometimes used during pregnancy in women with high glucose and insulin levels to prevent or lessen the risk for gestational diabetes.

Metformin is not a weight loss pill. Lifestyle modifications including changes to diet and exercise need to be maintained for weight loss to occur.

Dosage Of Metformin

A dose of at least 1,000 mg of metformin is usually required to see an effect, and dosages up to 3,000 mg are commonly given.

It is important to take metformin exactly as prescribed, as titration is usually required while initiating treatment. That means that you may take one pill a day for a short amount of time, then increase the dose to two pills a day for a short while, then continue to increase in short increments until the prescribed dose is achieved.

Metformin should always be taken with food.

Side Effects To Know

Side effects that you may experience while taking metformin include diarrhea, nausea or vomiting and abdominal cramping. The most common side effect is diarrhea. Taking metformin with food can minimize side effects. Eating processed and refined foods or too many carbohydrates at once while taking metformin can increase the likelihood of side effects occurring.

If you cannot tolerate these side effects, notify your doctor as he might be able to change the medication or dose that you take. You may need a blood test prior to starting metformin, and periodically during treatment to assess liver and kidney function. Metformin may lower your blood sugar, and if you are not eating (taking in sugar), it may make you sick.

Metformin can affect the absorption of vitamin B12. Long-term use and high doses of metformin increase the likelihood of a vitamin B12 deficiency. A lack of vitamin B12 can cause mood changes, memory loss and can cause permanent damage to the brain and nervous system. You should supplement your diet with vitamin B12 and have your levels checked annually. Optimal ranges of vitamin B12 should be >450 pg/mL. Elevated serum homocysteine and urinary methylmalonic acid (MMA) levels, the gold standard in assessing B12, also indicate a B12 deficiency.

Lactic acidosis is a rare side effect of metformin. Drinking alcohol while on metformin is not recommended.


Bailey, C. and Turner, R. Metformin. N Engl J Med. 1996; 334: 574–579

Zhuo Z, Wang A, Yu H. Effect of metformin intervention during pregnancy on the gestational diabetes mellitus in women with polycystic ovary syndrome: a systematic review and meta-analysis. J Diabetes Res. 2014;2014:381231.

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