Use of metformin for ovulation induction in women who have polycystic ovary syndrome with or without evidence of insulin resistance.

Objective: To determine whether women with polycystic ovary syndrome (PCOS) and abnormal insulin levels treated with metformin had different rates of ovulation and pregnancy from women with PCOS and normal insulin levels.

Methods: The outcomes of treatment with metformin in 146 infertile women with PCOS were analyzed using a retrospective cohort study design. Baseline characteristics and initial blood work results were recorded. The follow-up period was three months, and the primary outcome was ovulation.

Results: Of the 146 women with PCOS, one third had elevated fasting insulin levels. After treatment with metformin, cumulative rates of ovulation were similar in women with elevated fasting serum insulin levels (48.8%) and those with normal levels (44.7%). Rates of ovulation were also similar in women with normal and abnormal glucose to insulin ratios. There was no difference in cumulative pregnancy rates based on fasting insulin levels. A fasting insulin level above 20 mU/L correlated with an abnormal glucose to insulin ratio (98%).

Conclusion: In anovulatory women with PCOS, fasting insulin levels and glucose to insulin ratios do not predict the ovulatory response to metformin.