Relationship of high leptin levels with an adverse lipid and insulin profile in 6-8 year-old children in Spain.

BACKGROUND AND AIMS: Leptin, an adipokine elevated in obesity, may be related to an adverse cardiovascular risk profile in childhood. However, evidence for this relationship in pre-pubertal children is scarce. We aimed to analyze the relationship between leptin levels and lipid and insulin profiles in Spanish children. METHODS AND RESULTS: Our population-based sample included 389 males and 369 females aged 6-8 years. Lipid levels were determined by standard methods, insulin by radioimmunoassay and leptin by sandwich ELISA. Leptin levels were higher in girls (8.6 ng/ml) than boys (4.7 ng/ml) (p < 0.001). Leptin increased from ages 6 to 8 in girls, but remained steady in boys. In both sexes, leptin increased significantly (p < 0.001) across weight category from normal weight to obese. Children in the highest tertile of leptin concentration showed significantly (p < 0.01) lower levels of HDL-cholesterol (HDL-C) and apolipoprotein-AI (apo-AI) and significantly higher triglyceride (TG) levels than children in lower tertiles. However, in linear regression analysis, after adjustment for body mass index (BMI), leptin only accounted for 1.5% of the variance of HDL-C in boys, and 2.6% of the variance of apo-AI in girls. Leptin was strongly and positively correlated with insulin and HOMA. Upon regression analysis, leptin contributed to over 20% of the variability in insulin and HOMA, independent of BMI. CONCLUSION: Leptin levels show sex differences in pre-pubertal children. In this age group, leptin levels are strongly related to insulin, and affect lipid profile -namely HDL-C, apo-AI and TG- particularly when leptin levels are high.

High tracking of apolipoprotein B levels from the prepubertal age to adolescence in Spanish children.

AIM: To assess tracking of lipid and apolipoproteins from the prepubertal age (baseline, 6-8 years old) to adolescence (follow-up, 13-16 years old) in Spanish children. METHODS: The sample population included 385 healthy children (179 boys and 206 girls). Tracking was estimated by correlations between baseline and follow-up levels, multiple regression models in which the follow-up lipid was the dependent variable and analysing the percentage of individuals who remained in the same lipid levels status from prepubertal age to adolescence. RESULTS: Correlations between baseline and follow-up levels for low density lipoprotein (LDL)-cholesterol and apolipoprotein B (apo B) were stronger in boys and for high density lipoprotein-cholesterol and apo A-I stronger in girls. Regression analyses showed that, after adjusting by body mass index (BMI), baseline LDL-cholesterol and apo B levels explain 23% and 39% of the variation of follow-up LDL-cholesterol and apo B levels, respectively, in boys and 13% and 22%, respectively, in girls. The strength of tracking for LDL-cholesterol and apo B was 79% and 89%, respectively, in boys and 72% and 82%, respectively, in girls. CONCLUSION: Apolipoprotein B showed the strongest tracking in both sexes, stronger than for LDL-cholesterol, which supports the importance of determining apo B levels as a marker of dyslipidaemia in children.

Differences in the implications of maternal lipids on fetal metabolism and growth between gestational diabetes mellitus and control pregnancies.

AIMS: To evaluate the potential contribution of maternal glucose and lipids to fetal metabolic variables and growth in pregnancies with normal glucose tolerance in comparison with pregnancies with well-controlled gestational diabetes previously reported by us. METHODS: In 190 pregnancies with normal oral glucose tolerance tests (controls), insulin, glucose and lipid components were determined in maternal and arterial cord blood serum. Birthweight and neonatal fat mass were obtained after delivery. Values were adjusted for maternal pre-pregnancy BMI, Caesarean section and gestational age. Measurements were compared with those of gestational diabetes previously reported. RESULTS: Maternal serum glucose, triacylglycerol, free fatty acid and cholesterol levels did not differ between control pregnancies and those with gestational diabetes, whereas insulin, homeostasis model assessment and glycerol values were significantly lower in the former (2.6 vs. 5.6 µmol/l and 176 vs. 193 µmol/l, respectively). In contrast, cord blood glucose and free fatty acids were significantly lower in control pregnancies than in those with gestational diabetes (3.9 vs. 4.4 mmol/l and 80.7 vs. 137 µmol/l, respectively); the same was valid for insulin (0.03 vs. 0.05 nmol/l) and homeostasis model assessment (1.0 vs. 1.87). In control pregnancies, maternal serum glucose, free fatty acids and glycerol correlated with those in cord blood, but not with neonatal weight and fat mass, as seen for free fatty acids in those with gestational diabetes. The negative correlation between cord blood triacylglycerols and neonatal weight or fat mass previously reported in gestational diabetes could not be confirmed in control pregnancies, where all fetal lipids showed a positive correlation to neonatal anthropometrics. CONCLUSION: In normal pregnancies, in contrast to those with gestational diabetes, maternal lipids do not influence neonatal weight. Similar levels of maternal lipids in pregnancies with gestational diabetes and control pregnancies, but higher free fatty acids in the cord blood of those with gestational diabetes, indicate their enhanced placental transport and/or enhanced lipolysis as a result of decreased fetal insulin responsiveness.