To investigate the effect of long-term androgen suppression on insulin sensitivity, obese and non-obese women with the polycystic ovary syndrome and obese and non-obese ovulatory women were given an oral glucose tolerance test before and after treatment with a gonadotropin-releasing hormone agonist. The women with polycystic ovary syndrome showed higher basal luteinizing hormone and androgen levels than the ovulatory women. All women with the polycystic ovary syndrome responded non-diabetically to the glucose tolerance test. However, compared with controls, the obese women with the polycystic ovary syndrome showed a hyperinsulinemic response to the glucose tolerance test, indicating insulin resistance. During the 3-h glucose tolerance test there was no concomitant change in androgen levels in the hyperinsulinemic women with the polycystic ovary syndrome. The insulin response to an oral glucose tolerance test remained unchanged in all women, although a hypogonadotropic hypogonadal state was maintained for several weeks. This study therefore suggests that endogenous androgens do not play a role in sustaining insulin resistance in women with the polycystic ovary syndrome.