Using a simple and standardized method we estimated both insulin secretion and insulin sensitivity in peripheral tissues in relation to Tanner pubertal stages. Early insulin response, mean blood glucose (MBG), mean serum insulin (MSI), glucose uptake rate in peripheral tissues and insulin sensitivity index (SI) in response to the standard oral glucose tolerance test were evaluated in 73 normal girls. Study subjects were divided into 4 groups: group 1 (Tanner stage I, n = 20); group 2 (Tanner stage II, n = 14); group 3 (Tanner stages III and IV, n = 15), and group 4 (Tanner stage V, n = 24). Steroid levels and insulin-like growth factors were determined to characterize clinical pubertal development. MBG was similar in all groups but MSI increased at stage II and retained similar values throughout puberty, with those of group I being statistically lower than in the other groups (p < 0.001). When MSI values were adjusted per kilogram of body weight, a significant increase was observed in group II (p < 0.05). The MSI adjusted values were: group 1 1.0 ± 0.4; group 2, 1.4 ± 0.4; group 3, 1.0 ± 0.3, and group 4, 1.0 ± 0.4 mU/l/kg. SI values were similar in groups 1 and 2 and significantly lower than in groups 3 and 4 (p < 0.001). Our results confirm both that insulin secretion is related to age and that an insulin-resistant state occurs during puberty. Thus, the insulin-resistant state coincides with Tanner stage II. In conclusion, this mathematical approach is considered to be a simple and reliable method for analyzing the possible alterations in insulin secretion and action in children and adolescents in whom more sophisticated procedures must be limited in this early period of life for ethical reasons.

The fasting insulin resistance index, mean blood glucose, mean serum insulin (MSI), early insulin response to glucose, glucose uptake rate in peripheral tissues, and insulin sensitivity indexes in response to a standard oral glucose tolerance test; serum insulin-like growth factor I (IGF-I), IGF-binding protein-1 (IGFBP-1), IGFBP-3, and sex hormone binding-globulin (SHBG) levels; and the free androgen indexes were evaluated in 98 girls with premature pubarche [PP; prepubertal (B1; n = 32), early pubertal (B2; n = 27), midpubertal (B3; n = 23), and postmenarcheal (B5; n = 16)] and in 86 Tanner stage- and bone age-matched controls. We ascertained whether hyperinsulinemia is already present in PP girls before or during pubertal development and whether these patients show a similar pattern of growth factor secretion as normal girls. Body mass indexes did not differ significantly between patients and controls within the same pubertal stage. MSI levels showed a significant increase with pubertal onset in all subjects, as expected. Patients showed significantly higher MSI values than controls at all Tanner stages (P < 0.03, P = 0.03, P = 0.03, and P < 0.05 for B1, B2, B3, and B5, respectively); higher insulin response to glucose at B1, B2, and B3 (P < 0.03, P = 0.03, and P < 0.05, respectively); higher glucose uptake rate in peripheral tissues at B1 and B2 (P < 0.04 and P = 0.02, respectively); and a later rise in insulin sensitivity compared to controls. PP girls also showed lower IGFBP-1 levels at B1 and B5 (P < 0.01 and P = 0.02, respectively), lower SHBG concentrations at B5 (P < 0.0005), and higher free androgen indexes at B1, B3, and B5 (P < 0.01, P < 0.05, and P < 0.001, respectively) compared to controls. Among others, significant correlations between SHBG and MSI levels (r = -0.49; P < 0.0001) and between SHBG and IGFBP-1 levels (r = 0.41; P < 0.0001) were found in all subjects. Hyperinsulinemia, increased early insulin responses to glucose, increased glucose uptake rate in peripheral tissues, elevated free androgen indexes, and decreased SHBG and IGFBP-1 levels are present in most girls with PP from childhood. These findings lend strong support to the concept that PP is not a benign condition, and long term follow-up of these patients into adulthood is recommended. The possible causal role of hyperinsulinemia in adrenal and/or ovarian androgen hypersecretion remains to be established.

In girls, pronounced adrenarche with precocious pubarche (PP) has been related to reduced fetal growth and to a cluster of endocrine-metabolic abnormalities. We examined whether these associations are also evident in boys with PP. The study population consisted of matched groups of boys (n = 58; age range 5–15 years) without or with a history of PP. After stratification for pubertal development, non-PP and PP boys displayed comparable results for the studied variables, including serum insulin-like growth factor I, sex hormone binding globulin, insulin-like growth factor binding proteins 1 and 3, indices of circulating glucose and insulin responsiveness to an oral glucose load, and birth weight SD score. In conclusion, the present results indicate that adrenarche-driven PP in boys is, in contrast to PP in girls, not associated with a cluster of endocrine-metabolic abnormalities and is not related to reduced fetal growth. These observations support the view that adrenarche-driven PP in boys may be regarded as a variant of normal development.

Background: Reduced fetal growth is a potential risk factor for development of metabolic abnormalities in later life. The relationship between low birthweight and impaired glucose tolerance, type 2 diabetes and insulin resistance in adulthood has been well documented. Purpose: Assuming that fetal undernutrition is associated with insulin resistance in middle age, we elected to study whether this process may already be present in young adults andadolescents born small for gestational age (SGA). Subjects and Methods: Children born in Vall d’Hebron Hospital Infantil, Barcelona, between 1986 and 1989 and between 1978 and 1983 with birthweights below the third centile for the local standard values, were invited to participate in the present study. Of those, 51 (22 girls and 29 boys) were pre-pubertal with 9.4 ± 0.2 years of age and 49 (29 girls and 20 boys ) were post-pubertal, with 17.3 ± 0.3 years of age. All patients underwent a standard, 2-hour oral glucose tolerance test. Insulin and glucose responses were compared with our previously published data in control children with normal birthweight. Results: The insulin response at 30 min after glucose load was significantly higher (p < 0.001) in pre- and post-pubertal girls and boys formerly SGA than in controls. In addition, the girls also had a higher insulin response at 60 and 120 min. Mean serum insulin (MSI), the area under the insulin curve during the glucose challenge, was statistically increased in pre- and post-pubertal boys and girls born SGA when compared to controls. Conclusion: The presence of high insulin levels after an oral glucose challenge in children and adolescents born SGA might be considered as an early marker of subsequent insulin resistance in adulthood. Furthermore, our population offers the opportunity to study the natural course of hyperinsulinemia and its outcome. Follow-up of this cohort may be helpful in distinguishing a subset of young children and adolescents in whom therapeutic intervention could be done.