Fasting plasma insulin level is an important risk factor for the development of complications in Japanese obese children—Results from a cross-sectional and a longitudinal study

Abstract

It is not known what types of factors may contribute to the development of complications in obese children. In the current investigation, we have performed a cross-sectional and a longitudinal study in Japanese obese children to clarify the relationship of the extent of obesity, fat distribution, insulin resistance, and aging to the development of obesity-related complications. In the cross-sectional study of 329 obese boys and 142 obese girls aged 7 to 15 years, the fasting plasma immunoreactive insulin (IRI) level was significantly higher than that of 46 non-obese boys and 48 non-obese girls (boys, 13.4 ± 6.7 v 4.9 ± 1.9 μU/mL, P < .001; girls, 14.0 ± 5.9 v 4.8 ± 1.8, P < .001). Linear regression analysis demonstrated that fasting plasma IRI correlated positively with fasting plasma glucose (FPG), triglycerides (TG), uric acid (UA), and systolic blood pressure (SBP) in obese boys, and with TG, SBP, and diastolic blood pressure (DBP) in obese girls, and negatively with serum high-density lipoprotein cholesterol (HDL-C) in both obese boys and girls. Multiple regression analysis demonstrated that fasting plasma IRI was independently and positively correlated with FPG, TG, and SBP in obese boys. Fasting plasma IRI in obese girls was positively correlated with TG, SBP, and DBP, and negatively with HDL-C. FPG decreased significantly in non-obese children at the onset of puberty, but it remained unchanged in obese children. Fasting plasma IRI and the IRI to glucose ratio increased with age in obese children, whereas they did not show any significant changes in non-obese children. Furthermore, in the longitudinal study of 42 obese children (32 boys and 10 girls) aged 7 to 15 years, significant increases in FPG ( P < .01), insulin, UA, and SBP ( P < .001, respectively) and a significant decrease in serum HDL-C ( P < .001) were observed. Significant positive correlations were also noted between the yearly changes for IRI and SBP, and between the changes for IRI and the number of obesity-associated complications. These results suggest that fasting plasma IRI can be one of the most useful indices for predicting the development of obesity-associated complications in children, especially hypertension, hyperlipidemia, and hyperuricemia.