Behavior of Insulin Resistance and Its Metabolic Correlates in Prepubertal Children

Abstract

Secular trends in childhood obesity suggest that many children are gaining excess fat, thereby contributing to an emerging epidemic of type 2 diabetes in young people (1,2). However, it is normal for children to accumulate some fat in the years before puberty (3). These considerations highlight the difficulty in distinguishing pathological from physiological fat accumulation. Longitudinal data in healthy children are required in order to properly examine the relationships between adiposity and metabolic health. We prospectively studied a cohort of healthy prepubertal British school children and report here some unexpected temporal relationships between adiposity and insulin resistance. EarlyBird is a prospective nonintervention study investigating the emergence of insulin resistance in childhood. A cohort of 307 healthy children was recruited in 2000–2001 from randomly selected schools in Plymouth, U.K. Most are Caucasian, with a wide socioeconomic mix. Mean ± SD age at recruitment was 4.9 ± 0.25 years. The protocol has previously been described in detail (4). Results are reported for the first 4 study years, when the children were aged 5, 6, 7, and then 8 years. Only children who attended at all four time points (130 boys and 100 girls) were included for analysis. Those excluded (40 boys and 37 girls) did not differ anthropometrically or in metabolic measures at age 5 years ( t tests; all P > 0.05). The male preponderance resulted from random recruitment. Results are presented separately by sex. ### Annual measures Annual measures included height, weight, BMI standardized to 1990 U.K. reference data (SD scores), sum of five skinfolds (SSF) (skinfolds measured twice over biceps and triceps of the left arm and the subscapular, suprailiac, …