Metformin for individuals with polycystic ovary syndrome
Metformin improves glucose metabolism by decreasing glucose production in the liver and increasing glucose uptake in tissues. Although specific evidence of its impact on insulin resistance in polycystic ovary syndrome (PCOS) is limited, it can be considered for individuals with PCOS who have:
- a high risk of developing type 2 diabetes, even if tests of glucose metabolism are normal
- subfertility in an individual with irregular menstrual cycles (despite lifestyle change)
- a body mass index (BMI) greater than 25 kg/m2 if insufficient weight is lost after a 6-month trial of lifestyle changes (metformin does not cause significant weight loss but may prevent weight gain); see also Weight control in PCOS.
Metformin also suppresses ovarian androgen production, which improves the frequency of ovulation in individuals with PCOS. Although it is not recommended for managing irregular bleeding, it can be used in managing subfertility.
If metformin is indicated, use:
1 metformin immediate-release 500 mg orally, daily with evening meal as an initial dose; increase daily dose by 500 mg every 1 to 2 weeks as tolerated, up to a maximum of 1500 mg daily in 2 or 3 divided doses polycystic ovary syndrome metformin
OR
2 metformin modified-release 500 mg orally, daily with evening meal as an initial dose; increase daily dose by 500 mg every 1 to 2 weeks as tolerated, up to a maximum of 1500 mg daily. metformin
Most studies of metformin for PCOS used immediate-release metformin. Gastrointestinal effects of immediate-release metformin can be minimised by starting treatment at a low dose, titrating gradually, and taking with food. If this is not tolerated, modified-release metformin may be used.
If type 2 diabetes is diagnosed in an individual with PCOS, see Metformin for adults with type 2 diabetes for information on metformin dosage, mode of action and adverse effects.