Therapeutic Effect of Metformin on Patients with Polycystic Ovary Syndrome with Normal Insulin Sensitivity: A Retrospective Study

Objective:This study aimed at elucidating the therapeutic effectiveness of metformin in polycystic ovary syndrome(PCOS)patients with normal clinical indices of insulin sensitivity.Methods:This study was a retrospective cohort study.Based on their homeostasis model of assessment of insulin resistance(HOMA-IR)results,PCOS patients(n=113)were allocated to either the IR Group(IR,HOMA-IR>2.69)or the non-IR Group(NIR,HOMA-IR≤2.69).Metformin was administered to all patients,and their medical history,menstrual status,and endocrine and metabolic characteristics were obtained before and after treatment.The one-way analysis of variance was used to determine the differences between the IR and NIR groups.The paired t-test was used to determine the differences between pre-and posttreatment results.Results:Analyses of baseline characteristics showed that the incidence of IR and glycolipid metabolism is higher within elder PCOS patients.Metformin improved menstrual cycle and ovulation rate in NIR patients,similar to those in IR patients.In the NIR group,metformin decreased luteinizing hormone(LH)levels,free androgen index(FAI)levels,body mass index,and waist circumference,but had no obvious effect on glucose,insulin,and lipid profiles.Whereas in the IR group,metformin not only decreased LH and FAI levels,but also improved glycolipid metabolism.Conclusions:The effect of metformin on PCOS patients with normal insulin sensitivity index suggests that the mechanism of menstrual improvement may not be related to IR.In addition,metformin can improve glycolipid metabolism.Therefore,metformin is suitable for long-term treatment of PCOS and should be more widely used.