Evaluation of fasting serum insulin levels among Japanese school-age children.

We examined the physical constitution, serum lipids, fasting serum insulin (IRI), food intake, and physical activity in 1,330 children in three age groups (6-7, 9-10, and 12-13) in Nagao village for the period 1994-1996. Serum total cholesterol (TC) and high-density lipoprotein-cholesterol (HDL-C) levels were positively correlated, and HDL-C and TG were negatively correlated in all age groups. IRI was significantly higher among the elder children, and it was also higher in girls than in boys. IRI was positively correlated with the body mass index (BMI) and triceps skinfold thickness in ages 9-10 and 12-13, but no significant correlation was noted with waist/hip ratio (W/H ratio). In ages 12-13, IRI was positively correlated with TC and TG and negatively correlated with HDL-C. In high-IRI children (above 11.4 microU/mL) ages 12-13, the high-fat diet (fat-energy ratio above 30%) and low physical activity children (physical activity score below 10 points) were more frequent, and the mean levels of triceps skinfold were higher. The positive correlation between TC and HDL-C was not significant among high-IRI children. We concluded that a high-fat diet, low physical activity, and body fat accumulation influence the IRI level, which is closely related to serum lipid levels.