Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in reproductive age women. Women with PCOS have a high risk of prediabetes, type 2 diabetes and heart disease. The investigators have found a possible change in the DNA (genes of the body that encode all of our traits) that seems to be related to insulin resistance. In this study, the investigators will try to determine whether the change in the gene affects a woman's ability to respond to a common treatment for PCOS, metformin.