Background: Insulin resistance and the associated compensatory hyperinsulinemia
are common findings in women with PCOS, and may play a key role in this condition.
Methods: In this article, we focused on the significance of insulin resistance in PCOS, reviewing
the available literature on epidemiology, pathogenesis, pathophysiology and treatment
of this condition.
Results: It has been estimated that approximately 70% of these women are insulin resistant,
but this figure is affected by frequent referral bias. In addition, there is metabolic heterogeneity
between clinical phenotypes of PCOS. A fundamental issue is the role that hyperinsulinemia
plays in androgen overproduction, which is enhanced by bidirectional links between
insulin resistance and hyperandrogenism. Available data suggest that women with PCOS
may have insulin action alterations of heterogeneous origins, which induce specific abnormalities
in these subjects due to the presence of intrinsic defects. Obesity is a common finding in these patients
and contributes to the association between PCOS and insulin resistance, combining with the effect of PCOS per
se. Insulin sensitization shows several beneficial effects in the treatment of this condition. However, clinical response
Conclusion: Insulin resistance is a common feature of women with PCOS, although it is not universal and differ
between clinical phenotypes of PCOS. Insulin resistance and hyperandrogenism appear to be interrelated key
factors in the pathogenesis of PCOS. We hypothesize that PCOS might represent a common end-stage clinical
phenotype of different processes, in which there are impaired insulin action and hyperandrogenism, probably
favoured by specific, intrinsic abnormalities of these women.