Insulin resistance occurs when certain tissues, primarily skeletal muscles, do not respond to insulin. This results in a compensatory increase in the secretion of insulin by the pancreas, causing an increase in the serum concentrations of insulin (hyperinsulinemia). Hyperinsulinemia can lead to the excess production of androgens through a number of pathways, including stimulation of the hypothalamus, stimulation of the adrenal glands (adrenal gland) and the ovaries, and suppression of the circulating levels of sex-hormone-binding globulin, which allows androgens to readily leave the circulation and enter tissues (e.g., hair follicles) where they exert their actions. Insulin resistance and compensatory hyperinsulinemia are also risk factors for other metabolic diseases, including type II diabetes (diabetes mellitus) and atherosclerosis, which women with Stein-Leventhal syndrome may develop at an unusually young age. In addition, obesity is present in about 50 percent of affected women and is often associated with the presence of other metabolic problems. Hyperinsulinemia, obesity, and chronic anovulation may also lead to the development of endometrial cancer ( uterine cancer).

The syndrome may become apparent at or prior to puberty, at which time symptoms may include premature development of pubic hair, hyperinsulinemia, and elevated levels of precursor molecules that can be converted to androgens. After puberty, symptoms may include infrequent or absent menstrual cycles (menstruation), infertility, and signs of excess levels of androgens, including hirsutism (excessive midline body hair) and acne. As affected women grow older, menstrual irregularity and androgen excess become less of a problem, with these symptoms often improving after the age of 40. In fact, diagnosis of the syndrome is difficult to make after the onset of menopause. Because affected women exhibit a wide variety of signs and symptoms, some authorities believe that the syndrome is not one but several different syndromes. In addition, no genetic cause has been identified, although the syndrome sometimes appears in multiple women in one family.

The most basic form of treatment of women with Stein-Leventhal syndrome is the initiation of an exercise regimen combined with proper nutrition to encourage weight loss and to improve insulin sensitivity. If these measures are unsuccessful, or if the syndrome is severe, treatment is focused on suppressing excess androgen production. In women who do not wish to become pregnant, hirsutism and menstrual irregularities can be managed with oral contraceptives (contraception) or anti-androgen drugs. In women who do wish to become pregnant, infertility is often treated with drugs that induce ovulation, such as clomiphene citrate or gonadotropins. Less commonly, laparoscopic surgery (laparoscopy) is used to destroy portions of the ovary and thus reduce the production of androgens. In addition, antidiabetic drugs have been used in some patients to increase ovulatory frequency and to decrease excess androgen levels.