The Role of Insulin Resistance in PCOS

Polycystic ovary syndrome (PCOS) phenotype can be structured into three components: anovulation, hyperandrogenism and the metabolic syndrome (of which hyperinsulinemia, secondary to insulin resistance, is the central abnormality)(1). It is the most common endocrinologic disease seen in Gynecologic clinic. The follicular excess in polycystic ovaries and the failure of selection of one dominant follicle contribute to the anovulation of PCOS. The infertile PCOS female usually suffered from difficult ovulation induction and high risk of ovarian hyperstimulation syndrome because of extensive stimulation.

PCOS is the main androgen disorder in women and has been suggested to be associated with a high risk of developing cardiovascular disease and type-2 diabetes. In many PCOS patients, overweight or central obesity is generally associated with increases in fasting insulin levels, insulin resistance, and glucose intolerance, and has been identified as a target for new therapeutic strategy, including early change in lifestyle.

Insulin resistance, defined as decreased insulin-mediated glucose utilization, is commonly (10-25%) found in the normal population. In women with PCOS, insulin resistance appears even more common (up to 50%), in both obese and non-obese women.Hyperinsulinemia appears to play a key pathogenic role in the ovarian androgen overproduction, because of the stimulatory effect of insulin on ovarian steroid production.