Previous studies have documented the association of insulin resistance and hyperandrogenism in adult women with functional ovarian hyperandrogenism (FOH) or polycystic ovary syndrome (a form of FOH). However, the possible impact of adrenal hyperandrogenism development during childhood in premature pubarche (PP/patients on postpubertal insulin secretion patterns remains unclear. The fasting insulin to glucose ratio, C peptide, early insulin response to glucose (IRG), mean blood glucose, mean serum insulin (MSI), glucose uptake rate in peripheral tissues (M), and insulin sensitivity indexes (SI) in response to a standard oral glucose tolerance test were evaluated in 13 PP girls with FOH (group A; age, 17.2 ± 0.5 yr), 11 eumenorrheic nonhirsute PP girls (group B; age, 16.6 ± 0.5 yr), and 21 age- matched controls (group C). Body mass indexes (BMI) were similar in the 3 groups (group A, 23.3 ± 0.8; group B, 22.5 ± 0.6; group C, 20.6 ± 0.5 kg/m2). MSI values were significantly higher in FOH patients than in controls (74.7 ± 17.6 vs. 46.7 ± 4.1 mU/L; P < 0.01), but were not different from those in group B (63.3 ± 11.1 mU/L). Thirty-eight percent of FOH patients (group A) and 27% of non-FOH patients (group B), all of whom had normal BMI, showed MSI levels well above the upper normal limit for controls (>83.3 mU/L). MSI correlated with the degree of ovarian hyperandrogenism [defined by an abnormal 17-hydroxyprogesterone response to challenge with the GnRH analog leuprolide acetate; group A) and with the free androgen index [testosterone (nanomoles per L)/sex hormone-binding globulin (nanomoles per L) x 100; groups A and B)]. Although IRG, glucose uptake rate in peripheral tissues, mean blood glucose, and SI values were not significantly different in the 3 groups, 3 patients in group A and 1 patient in group B showed decreased insulin sensitivity and/or an enhanced early IRG. Among others, significant correlations between MSI and free androgen index values (r = 0.6; P < 0.002; groups A and B) and between BMI and SI (r = -0.53; P < 0.05; groups A and B) were found. Peak 17-hydroxyprogesterone responses to ACTH at PP diagnosis correlated positively with SI in both groups of patients (r = 0.53; P < 0.007). Hyperinsulinemia is a common feature in adolescent PP patients with FOH and appears to be directly related to the degree of androgen excess. Long term follow-up of PP patients into adulthood is warranted to ascertain whether hyperinsulinemia actually precedes FOH development and whether overt insulin resistance ensues.