From the Guidelines
Metformin is likely to improve menstrual cyclicity and hyperandrogenism in female individuals with PCOS, particularly when used in addition to lifestyle modification. The typical starting dose is 500 mg once daily, gradually increasing to 1500-2000 mg daily in divided doses to minimize gastrointestinal side effects 1. For PCOS management, metformin helps improve insulin sensitivity, which can reduce testosterone levels, regulate menstrual cycles, and potentially improve ovulation rates. Women taking metformin for PCOS may experience benefits including weight loss, improved metabolic parameters, and reduced risk of developing type 2 diabetes.
Key Considerations
- Metformin works by decreasing liver glucose production and improving insulin sensitivity in peripheral tissues, addressing the insulin resistance that underlies many PCOS symptoms 1.
- Common side effects include nausea, diarrhea, and abdominal discomfort, which often improve with time or by taking the medication with meals.
- Extended-release formulations may cause fewer digestive issues.
- While not FDA-approved specifically for PCOS, metformin is widely prescribed off-label and works best when combined with lifestyle modifications like healthy diet and regular exercise.
- The association between obesity and PCOS is complex and bidirectional, and weight loss is recommended as part of management in individuals with PCOS with higher body mass index (BMI) 1.
Management Approach
- Evaluate for polycystic ovary syndrome in female adolescents with type 2 diabetes, including laboratory studies, when indicated 1.
- Consider metformin as an adjunct to lifestyle management for treatment of weight, hormonal and metabolic outcomes in PCOS, with a focus on prevention of weight gain 1.
- Lifestyle modifications, including diet and exercise, are challenging to maintain and often insufficient to lead to meaningful weight loss, making pharmacotherapy a recommended option in some cases 1.
From the Research
Metformin for PCOS: Benefits and Uses
- Metformin is widely used to manage type 2 diabetes and is commonly prescribed in polycystic ovary syndrome (PCOS) to address insulin resistance and associated metabolic and reproductive disturbances 2.
- In non-pregnant women, metformin improves insulin resistance, menstrual regularity, and androgen levels, particularly in those with obesity or insulin resistance, and may enhance fertility when combined with other treatments 2, 3, 4.
- Metformin is effective for restoring normal menstrual cycles in anovulatory PCOS patients and is more effective and cheaper than laparoscopic ovarian drilling as the second therapeutic step in PCOS patients previously defined as resistant to clomiphene citrate 3.
Metformin and Pregnancy
- In pregnancy, metformin may reduce early pregnancy loss, miscarriage, and preterm birth, though findings for gestational diabetes and preeclampsia are inconsistent 2.
- Metformin is considered safe for use in women with PCOS and may lower the risk of early pregnancy loss and preterm birth 2.
- However, its effects on preventing gestational diabetes or high blood pressure are less clear, with mixed results across studies 2, 5.
Guidelines for Metformin Use in PCOS
- The current Endocrine Society Guidelines recommend the use of metformin during adolescence, particularly when excess body weight is present 6.
- Metformin may have significant benefits in the presence of obesity and glucose intolerance states, particularly if those patients fail to modify their lifestyles 6.
- Metformin should not be used as a first-line treatment for ovulatory dysfunctions in adult women with PCOS, but pretreatment with metformin may favor ovulatory response to clomiphene citrate 6, 5.