Hyperinsulinaemia and polycystic ovary syndrome

Over the past 20 years, it has been established that hyperinsulinaemia is a fundamental disturbance in many women with polycystic ovary syndrome (PCOS). A subgroup of women with this syndrome have 'metabolic PCOS' which can be considered to be a pre-diabetic state. Clinically, this subgroup is most easily identified in obese women with a strong family history of diabetes in whom menstrual disturbance is the predominant feature. There is an urgent need to define the more subtle features in young lean women with PCOS, in whom the metabolic syndrome is yet to emerge, which would enable the prediction of future health risks. The molecular mechanisms of insulin resistance leading to hyperinsulinaemia are now being elucidated. Abnormalities of both insulin secretion and intracellular insulin signalling have both been proposed in women with PCOS. Strategies to lower serum insulin concentrations include diet, exercise and possibly, oral insulin sensitizing agents such as metformin. Although the short-term efficacy of reducing hyperinsulinaemia in women with PCOS is clear, the best method to prevent the progression to diabetes later in life has not been defined.