This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

The objective this review are:
(1) to assess the effectiveness of insulin‐sensitising drugs versus the combined oral contraceptive pill in improving symptoms of hirsutism and acne in PCOS;
(2) to assess the effectiveness of insulin‐sensitising drugs versus the combined oral contraceptive pill in lowering the risk of developing type 2 diabetes mellitus, cardiovascular disease (stroke, myocardial infarction), and endometrial cancer in women with PCOS;
(3) to assess the effectiveness of insulin‐sensitising drugs versus the combined oral contraceptive pill in improving other clinical (menstrual cyclicity, body weight, blood pressure), hormonal (androgens) and metabolic (glucose tolerance, insulin sensitivity and lipid levels) parameters
(4) to record and assess adverse side effects reported as a result of women with PCOS taking insulin‐sensitising drugs versus the combined oral contraceptive pill.