Introduction to Polycystic Ovary Syndrome (PCOS)

Insulin Resistance and Polycystic Ovary Syndrome

The origin of most symptoms associated with polycystic ovary syndrome (PCOS) is thought to be related to insulin resistance (IR). Insulin is a hormone that facilitates the absorption of glucose into the cells and in IR the body becomes increasingly less responsive the action of insulin. As a result, it takes more insulin to cause cells to absorb the appropriate amount of glucose. Eventually the insulin production may not be able to maintain the glucose within the normal range. Insulin resistance is associated with:

• Glucose intolerance

  The elevation of glucose in the blood is called glucose intolerance. The levels of blood glucose are higher than normal but lower than those found in diabetes.

• Hyperinsulinemia

  As the body tries to reduce the elevated glucose levels, the pancreas secretes increasing amounts of insulin. Insulin-resistant persons, therefore, develop high insulin levels in relation to glucose levels. This condition is called hyperinsulinemia.

  Increased insulin levels affect many functions. These include:

  • stimulation of the production of ovarian androgens leading to ovarian hyperandrogenism

  • lowering the levels of the liver protein, sex hormone binding globulin (SHBG) which may exacerbate symptoms of PCOS. Circulating androgens usually bind to SHBG, which renders them inactive. Women with PCOS have reduced levels of SHBG which results in more androgen circulating freely in the blood.

  Insulin resistance and its repercussions are suspected to be responsible for the endocrine, metabolic, and reproductive disorders/syndromes seen in many women with PCOS.

  • It is estimated that about 50% of women with PCOS are insulin resistant although the number may actually be higher.
  • Some estimates report that insulin resistance and hyperandrogenism are found in up to 60% of obese women with PCOS and in 40% of non-obese women with PCOS.
  • Impaired glucose tolerance occurs in approximately 20-40% of obese women with PCOS and in approximately 10% of normal weight women with PCOS.

There is strong evidence that IR, hyperinsulinemia, and glucose intolerance, are considered risk factors for Type II diabetes.