Insulin levels in prepubertal patients with isolated premature pubarche: the INPREPP study

We aimed to determine insulin levels and the homeostasis model assessment of insulin resistance (HOMA–IR) index in a cohort of children with isolated premature pubarche, to analyze the potential influence of adiposity, and to compare these parameters with those of a reference population. This study included 50 prepubertal patients with isolated premature pubarche between the ages of 5 and 8 yr (girls) and up to 9 yr (boys). Anthropometric parameters, abdominal circumference, body composition assessed by bioelectrical impedance analysis, and bone age were evaluated. Blood glucose, lipid profile, insulin, IGF-1, and androgen levels were measured. Standard deviation scores for insulin and the HOMA–IR index were calculated using age- and sex-specific reference values for our population.Among the participants, 76% were girls, and 20% had obesity. Insulin levels and the HOMA–IR index in normal-weight patients were similar to the population mean, whereas they were significantly increased in patients with excess adiposity. Higher levels were also observed in children who were formula-fed at birth compared with those who were breastfed, and in those with advanced bone age compared with those with bone age appropriate for chronological age; in both cases, this association was mediated by adiposity. The increase in insulin levels and the HOMA–IR index in patients with isolated premature pubarche appears to be influenced by adiposity.