The role of insulin–sensitising drugs in the treatment of polycystic ovary syndrome

Insulin-sensitising agents are frequently used in the treatment of women with polycystic ovary syndrome (PCOS) but, to date, the results have fallen short of expectations. Despite their limited benefits, these drugs are widely used in PCOS, and they are probably overprescribed. Insulin-sensitising agents are a class of drugs that work primarily or in part by improving peripheral insulin sensitivity to lower insulin levels and, ultimately, to lower circulating glucose levels. The classic example is the thiazolidinediones (pioglitazone and rosiglitazone). Given the intense endocrine interaction of tissues involved in glucose homeostasis, drugs that target one organ or function often have cross-over benefit on other aspects of glucose homeostasis. For instance, the biguanides primarily suppress hepatic gluconeogenesis but also exert some peripheral insulin-sensitising action, and it is this action that has led to the use of metformin in women with PCOS. While insulin-sensitising agents improve many symptoms and presenting complaints of women with PCOS, they do not represent a cure. They exert varying effects depending on the condition being treated. In many situations, there is no or only minimal benefit. The risk/benefit ratio for their use must thus be examined for each indication. This chapter explores the use of insulin sensitisers, primarily metformin, for varying indications related to PCOS and discusses the evidence to develop a risk/benefit ratio for their use. These drugs were developed to treat type 2 diabetes and have been adapted as treatments for the symptoms of PCOS.