This study examined the prevalence of both basal and glucose-stimulated hyperinsulinemia and acanthosis nigricans (AN) as well as the relationship between insulin and androgen levels in hyperandrogenic women. Sixty-two women who had an elevation of 1 or more plasma androgen levels were studied. The results in these women, grouped for analysis on the basis of obesity and ovulatory status, were compared to those in 36 control women of similar ages and weights. The anovulatory hyperandrogenic women had the clinical and biochemical features of the polycystic ovary syndrome (PCO). Oral glucose tolerance tests were performed with measurement of glucose, insulin, sex hormone-binding globulin (SHBG), and total and non-SHBG-bound sex steroid levels. AN was present in 29% of the hyperandrogenic women, the majority of them obese. Fifty percent of obese PCO women had AN, but they did not otherwise differ from PCO women lacking this dermatological change. Only women with PCO had significant hyperinsulinemia independent of obesity, and obese PCO women with AN had the highest serum insulin levels. Plasma glucose values during the oral glucose tolerance test were significantly increased in obese PCO women independent of the presence of AN, and 20% of these women had frank impairment of glucose tolerance. Ovulatory hyperandrogenic women had normal insulin levels and glucose tolerance. Obese and nonobese women had different relationships between sex steroid and insulin levels; obese women had significant correlations between insulin and non-SHBG testosterone levels (r = 0.30; P less than 0.05), whereas nonobese women had significant correlations between insulin and FSH (r = 0.40; P less than 0.01), dehydroepiandrosterone sulfate (r = 0.33; P less than 0.05), and SHBG (r = 0.37; P less than 0.05) levels, suggesting that the mechanisms underlying the association between sex steroid and insulin levels are complex. These findings suggest that 1) only women with PCO have hyperinsulinemia independent of obesity; hyperinsulinemia is not a feature of hyperandrogenic states in general; 2) AN is a common finding in obese hyperandrogenic women, particularly those with PCO; 3) only obese PCO women are at risk for impairment of glucose tolerance, independent of the presence of AN, suggesting that the negative impact of PCO and obesity on insulin action is additive; and 4) PCO women with AN can be considered as a subgroup of PCO and do not appear to have a distinct endocrine disorder.
We have investigated the hypothesis that hyperinsulinemia may cause the polycystic ovary syndrome (PCO) by directly stimulating gonadal steroidogenesis and/or gonadotropin secretion. 10 insulin-resistant women with PCO and 5 age-and weight-matched ovulatory normal women had pulsatile gonadotropin release, gonadotrope sensitivity to gonadotropin-releasing hormone, and sex hormone levels studied on two consecutive study days, basally and during the infusion of insulin (mean±SEM steady state insulin levels, 1,254±63 ,uU/ml PCO vs. 907±92 ,U/ml normal, P < 0.01). Insulin acutely increased mean delta (6 h minus prestudy) levels of androstenedione (A) (P c 0.001) and estradiol (E2) (P c 0.05) and decreased mean plasma pool (0-6 h) levels of testosterone (T) (P < 0.05), nonsex hormone binding globulin-bound T (P <0.05), and dihydrotestosterone (P < 0.01) in the PCO women. Insulin also decreased mean plasma 6 h A to estrone (El) ratios and increased 6 h El levels (both P c 0.05) in the PCO women. There were significant sequence effects (insulin + day) in the PCO women on T/E2 ratios, indicating a carryover action of insulin. Insulin had no effects on gonadotropin release in the PCO women. In the normal women, the only significant change was an insulin or study day effect that increased mean 6 h E2 levels (P < 0.01). There were significant spontaneous decreases in mean luteinizing hormone (P < 0.05) and follicle-stimulating hormone levels (P c 0.01) in the PCO but not the normal women on the second day of study. This study indicates that insulin can directly alter peripheral sex hormone levels independent of changes in gonadotropin release in insulin-resistant PCO women. Insulin decreased the levels of potent androgens in PCO women and did not increase androgen levels in normal women, arguing against a simple, direct causal relationship between hyperinsulinemia and hyperandrogenism in PCO.
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