Insulin level and insulin sensitivity indices among healthy children and adolescents.

INTRODUCTION: Information on insulin reference values and insulin sensitivity indices in the field of pediatrics is scarce.

OBJETIVE: To describe insulin range and insulin sensitivity surrogate indices during childhood.

POPULATION AND METHODS: Fasting insulin level range and surrogate indices, such as the homeostasis model assessment of insulin resistance (HOMA-IR), among healthy children and adolescents by age, body mass index, pubertal stage (PS), insulin-like growth factor-1 (IGF-1), total cholesterol, and triglycerides.

RESULTS: Two hundred and twenty-six healthy children and adolescents (1-18 years old) were included. Insulin increased with age, body mass index, pubertal stage, IGF-1 and triglyceride levels (r2= 0.38, p < 0.0001). Prepubertal children > 7.5 years old had higher insulin levels [median (P3 and P97) μIU/mL: 5.0 (1.7-9.6)] than prepubertal children ≤ 7.5 years old [2.9 μIU/mL (1.3-10.9), p < 0.01]. During puberty (from PS II to PS V), insulin was higher in girls than in boys [7.4 (1.8-16.9) versus 5.8 (1.8-12.9), p < 0.01]. The HOMA-IR index increased in the group of prepubertal children > 7.5 years old: 1.1 (0.32.0) versus children ≤ 7.5 years old: 0.6 (0.3-1.4, p < 0.01). The insulin level and HOMA-IR results were higher in pubertal children compared to the prepubertal group (p < 0.001).

CONCLUSIONS: Known physiological changes were observed inboth insulin levels and the HOMA-IR index among children and adolescents. A fasting blood insulin level of 10 μIU/mL in prepubertal children and of 17 μIU/mL and 13 μIU/mL in pubertal girls and boys, respectively, may be considered as an acceptable cut-off value in healthy children. A HOMA-IR value > 2.0 and > 2.6 in prepubertal and pubertal children, respectively, may be considered a warning sign for pediatricians to further investigate insulin resistance.