Insulin resistance (IR) is a condition whereby the body steadily becomes less responsive to the actions of insulin. A primary action of insulin is to regulate –lower — sugar, glucose, levels in the blood. In IR, blood sugar levels rise despite high levels of insulin and eventually type 2 diabetes results. This is in contrast to type 1 diabetes where the pancreas does not make sufficient insulin. Although the relationship of diabetes to other endocrine disorders is not new, only recently has the high preponderance of patients with PCOS with IR been recognized. It appears that hyperinsulinemia causes hyperandrogenism, rather than the reverse. The obese PCOS patient is more likely to have both IR and hyperinsulinemia, while the thinner individual does not show IR as often.

In terms of general metabolism, insulin facilitates storage of calories and increases fat stores. In addition, hyperinsulinism and IR have been suggested as a root of many unrelated disorders, such as chronic fatigue syndrome, defects in the immune system, eating disorders, hypoglycemia, gastrointestinal disorders, depression and anxiety. Presently, there is considerable investigation on Syndrome X (Metabolic Syndrome) which is characterized by insulin resistance and hypertension. Insulin resistance and hyperinsulinemia are considered to be significant risk factors in the development of atherosclerosis (hardening of the arteries). This predisposes PCOS individuals to increased risk of high blood pressure and stroke. Hyperinsulinemia results in an increase both LH release and androgen production with subsequent alterations in follicle growth.

Hyperinsulinemia is associated with androgen excess and a depressed level of sex steroid binding globulin (SHBG) IR has been associated with development of type 2 diabetes. In contrast to type 1 diabetes (previously called juvenile diabetes) where there is a pancreatic abnormality and low insulin production, with type 2 diabetes there is a strong family tendency to develop the disorder that is reminiscent of PCOS.