Insulin resistance, physical fitness, body composition and leptin concentration in 7–8 year-old children

Resting and exercise metabolic characteristics in obese children with insulin resistance

Purpose: This study aimed to explore the characteristics of resting energy expenditure (REE) and lipid metabolism during incremental load exercise in obese children and adolescents with insulin resistance (IR) to provide evidence for exercise intervention in obese children and adolescents with IR.

Method: From July 2019 to August 2021, 195 obese children and adolescents aged 13–17 were recruited through a summer camp. The participants were divided into IR (n = 67) and no-IR (without insulin resistance, n = 128) groups and underwent morphology, blood indicators, body composition, and resting energy consumption gas metabolism tests. Thirty participants each were randomly selected from the IR and no-IR groups to carry out the incremental treadmill test.

Results: Significant metabolic differences in resting and exercise duration were found between the IR and no-IR groups. In the resting state, the resting metabolic equivalents (4.33 ± 0.94 ml/min/kg vs. 3.91 ± 0.73 ml/min/kg, p = 0.001) and REE (2464.03 ± 462.29 kcal/d vs. 2143.88 ± 380.07 kcal/d, p < 0.001) in the IR group were significantly higher than in the no-IR group. During exercise, the absolute maximal fat oxidation (0.33 ± 0.07 g/min vs. 0.36 ± 0.09 g/min, p = 0.002) in the IR group was significantly lower than in the no-IR group; maximal fat oxidation intensity (130.9 ± 8.9 bpm vs. 139.9 ± 7.4 bpm, p = 0.040) was significantly lower in the IR group.

Conclusion: Significant resting and exercise metabolic differences were found between obese IR and no-IR children and adolescents. Obese IR children and adolescents have higher REE and lower maximal fat oxidation intensity than obese no-IR children and adolescents.

Effects of low-glycemic index diet on plasma adipokines in obese children

BACKGROUND

A low-glycemic index (GI) diet may modulate adipocyte-produced adipokines linking to insulin resistance.

METHODS

The stored plasma samples from the RCT of a low-GI vs. conventional diet in obese children were analyzed for adipokines: leptin, adiponectin, resistin, and visfatin. Their relationships with clinical outcomes were assessed.

RESULTS

Fifty-two participants completed the 6-month intervention trial (mean age: 12.0 ± 2.0 years, 35 boys). Both groups had significantly decreased BMI z-scores from baseline whereas the low-GI group had significant reduction in fasting insulin and HOMA-IR. There were no differences in adipokines between the groups before and after the intervention. However, there was an association between baseline leptin and the change of fat mass index (FMI) but not the insulin resistance in both groups. The higher the baseline leptin was, the lower the changes were for FMI after the intervention.

CONCLUSION

Despite no demonstrable effect of low-GI diet on plasma adipokines, the higher baseline leptin was correlated with lower reduction of fat mass. Leptin resistance may have a detrimental effect on the reduction of adiposity in obese children. Baseline leptin could be a useful predictor of the change in body composition in an obesity intervention trial.

IMPACT

Leptin resistance may have a detrimental effect in reducing the adiposity in obese children. This study is the first of its kind to compare the plasma adipokine concentrations of obese children on low-GI diet and conventional diet. We found that serum leptin was significantly correlated with the reduction of BMI z-score and FMI in both groups. Baseline leptin could be a useful predictor of the change in body composition in an obesity intervention trial.

Associations of physical activity and fitness with hepatic steatosis, liver enzymes, and insulin resistance in children with overweight/obesity

BACKGROUND

Non-alcoholic fatty liver disease is the most common liver disease in childhood and is related to insulin resistance and cardiometabolic risk factors. Evidence supporting the association of fitness and physical activity with hepatic fat, liver enzymes, or triglyceride-to-high-density lipoprotein ratio is scarce in children.

OBJECTIVE

To analyze the associations of physical fitness and physical activity (PA) with percentage hepatic fat, liver enzymes, insulin resistance, and cardiometabolic risk in children with overweight/obesity.

SUBJECTS

A total of 115 children (10.6 ± 1.1 years; 54% girls) with overweight/obesity of the EFIGRO study (ClinicalTrials.gov: NCT02258126) were included in the analyses.

METHODS

Cardiorespiratory fitness (CRF), musculoskeletal fitness and speed-agility were measured by the Alpha-fitness tests, and PA by wGT3X-BT accelerometers. Percentage hepatic fat was assessed by magnetic resonance imaging. Alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), aspartate aminotransferase (AST), insulin, glucose, triglycerides (TG), and high-density lipoprotein (HDL) levels were obtained from fasting blood samples. The homeostasis model assessment insulin resistance (HOMA-IR) and AST/ALT and TG/HDL ratios were calculated.

RESULTS

Higher CRF was associated with lower percentage hepatic fat (β = -0.266, P = .01) and GGT (β = -0.315, P < .01), and higher AST/ALT ratio (β = 0.306, P < .01). CRF-fit children have lower GGT levels (15 ± 1 vs 17 ± 1 U/L, CRF-fit vs CRF-unfit children, P = .02), HOMA-IR (2.2 ± 0.1 vs 2.9 ± 0.1, P < .01) and TG/HDL ratio (1.4 ± 0.1 vs 1.9 ± 0.1, P = .01) and higher AST/ALT ratio (1.3 ± 0.0 vs 1.2 ± 0.0, P = .03), than CRF-unfit children.

CONCLUSIONS

These findings emphasize the importance of considering the improvement of CRF as a target of programs for preventing hepatic steatosis, type 2 diabetes and cardiovascular diseases in children with overweight.

Leptin as a predictor of metabolic syndrome in prepubertal children

OBJECTIVE

Leptin has been suggested as a potential biomarker of cardiovascular risk. This paper aims to ascertain, based on a sample of prepubertal children, which serum leptin value best suited to identify metabolic syndrome (MS).

SUBJECTS AND METHODS

This observational, cross-sectional study recruited children from the outpatient pediatrics clinic, with the purpose of validating serum leptin level cutoffs to identify MS. All obese and overweight children who met eligibility criteria were included in the study, as was a sample of normal-weight children. The sample underwent clinical assessment and blood fasting glucose, lipid profile, insulin, and leptin were measured. Sensitivity and specificity were estimated for each leptin measurement, using MS as the outcome. These values were used to construct a receiver operating characteristic (ROC) curve. The association between MS and leptin was assessed using logistic models to predict MS.

RESULTS

A total of 65 normal weight, 46 overweight, and 164 obese children were analyzed (160 boys, 115 girls; age: 93.7 ± 17.8 months). The most appropriate leptin cutoff was 13.4 ng/mL (sensitivity 67.6%; specificity 68.9%; accuracy 72.1%). The logistic model indicated that leptin levels above 13.4 ng/dL were significantly associated with MS and that, for every 1 ng/dL increase in leptin levels, the odds of MS increase by 3% (p = 0.002; OR 1.03; 95% CI 1.01-1.05).

CONCLUSIONS

Leptin may be a useful biomarker of cardiovascular risk in prepubertal children, with an optimal cutoff of 13.4 ng/mL. Identification of potential new risk markers for cardiovascular disease in children could contribute to the development of preventive strategies.

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.

Potential programming of selected cardiometabolic risk factors at childhood by maternal polyunsaturated fatty acid availability in the MEFAB cohort

BACKGROUND

Increasing evidence suggests that long-chain polyunsaturated fatty acid (LCPUFA) availability in utero could program later health.

OBJECTIVE

The objective of the study was to explore whether prenatal LCPUFA availability could be involved in programming cardiometabolic disease risk at childhood.

METHODS

Data of 242 mother-child pairs from the Maastricht Essential Fatty Acid Birth (MEFAB) cohort were used. Multi-variable linear regression analysis was applied to identify associations between maternal LCPUFA concentrations around weeks 11, 22 and 32 of pregnancy and at time of delivery and cardiometabolic risk factors of their children (glucose metabolism, blood lipids, and blood pressure) at age 7.

RESULTS

Maternal eicosapentaenoic acid (20:5n-3) at week 11 of pregnancy was negatively associated with children׳s glucose (B=-0.34mmol/L; 95% CI: -0.56, -0.12). Positive associations were found between maternal linoleic acid (18:2n-6) at time of delivery and children׳s proinsulin (B=0.25pmol/L; 95% CI: 0.08, 0.41); maternal 3-docosapentaenoic acid (22:5n-3) at week 11 and children׳s total cholesterol (B=1.23mmol/L; 95% CI: 0.45, 2.01) and low-density-lipoprotein cholesterol (B=1.12mmol/L; 95% CI: 0.42, 1.82); and maternal osbond acid (22:5n-6) at week 22 and tetracosadienoic acid (24:2n-6) at week 32 and children׳s diastolic blood pressure (B=16.86mmHg; 95% CI: 7.63, 26.08 and B=17.75mmHg; 95% CI: 6.37, 29.94, respectively).

CONCLUSION

Our findings suggest that maternal omega-6 (n-6) fatty acids may be of particular importance in relation to children׳s glucose metabolism and blood pressure, whereas omega-3 (n-3) fatty acids seem particularly related to blood lipids at childhood. In general, the strength of the associations appeared stronger with fatty acid concentrations in early pregnancy compared to late pregnancy.

Adiposity, aerobic fitness, muscle fitness, and markers of inflammation in children

PURPOSE

The purpose of this study was to describe levels of inflammation markers in Norwegian children and to examine the associations of adiposity, aerobic fitness, and muscle fitness with markers of inflammation.

METHODS

In 2005-2006, 1467 nine-year-olds were randomly selected from all regions in Norway. The participation rate was 89%. The inflammatory markers evaluated included C-reactive protein (CRP), leptin, adiponectin, plasminogen activator inhibitor-1, tumor necrosis factor-α, hepatocyte growth factor, resistin, and interleukin-6. We assessed muscular strength by measuring explosive, isometric, and endurance strength. Aerobic fitness was measured directly during a maximal cycle ergometer test. Adiposity was expressed as waist circumference (WC).

RESULTS

The girls had significantly higher levels of CRP, leptin, adiponectin, and resistin and lower levels of tumor necrosis factor-α compared with the boys. We observed a graded association of CRP and leptin levels across quintiles of WC, aerobic fitness, and muscle fitness (P ≤ 0.001 for all participants). The regression analyses revealed that WC, aerobic fitness, and muscle fitness were independently associated with the CRP (WC β = 0.158, P < 0.001; aerobic fitness β = -0.190, P < 0.001; muscle fitness β = -0.122, P < 0.002) after adjustments for sex, age, Tanner pubertal stage, and the other independent variables. The same pattern was observed for leptin levels (WC β = 0.406, P < 0.001; aerobic fitness β = -0.298, P < 0.001; muscle fitness β = -0.064, P < 0.036).

CONCLUSIONS

These data represent a reference material with respect to inflammatory markers. Our results show that adiposity, aerobic fitness, and muscle fitness were independently associated with the CRP and leptin levels.

Development of a lifestyle-diet quality index for primary schoolchildren and its relation to insulin resistance: the Healthy Lifestyle-Diet Index

OBJECTIVE

The aim of this work was to develop an index that evaluates the degree of adherence to existing dietary and lifestyle guidelines for primary school-aged children (Healthy Lifestyle-Diet Index (HLD-Index)) and examine its relationship with selected nutrient intake and insulin resistance (IR).

METHODS

Ten components were used to develop the HLD-Index. Scores from 0 to 4 were assigned to all components. The HLD-Index total score ranged between 0 and 40. A sample of 729 schoolchildren from Greece aged 10-12 years (The Healthy Growth Study) was used to evaluate the validation of the proposed index.

RESULTS

The overall mean±standard deviation of the HLD-Index score was 20±4.4. Higher HLD-Index scores were associated with lower proportion of children having intakes lower than Estimated Average Requirements by Institute of Medicine. On the basis of the cutoff point of 3.16 for homeostasis model assessment of IR, 20.9% of participants were found to be insulin resistant. After adjusting for potential confounders, logistic regression showed that a 1 unit increase in the score is associated with almost 8% lower odds for being insulin resistant. The cutoff point analysis revealed that score equal to or lower than 21 best discriminates children with IR from those without IR. On the basis of this cutoff point, the sensitivity of the HLD-Index was 70% and the corresponding specificity was 47%.

CONCLUSIONS

The proposed HLD-Index could be used by public health policy makers and other health-care professionals to identify subgroups in the population with poor diet-lifestyle habits who are at increased probability for IR.

Childhood hypo-adiponectinaemia but not hyper-leptinaemia is associated with insulin insensitivity 6 years later

BACKGROUND

Biomarkers of metabolism and inflammation may predict children with increased diabetes risk.

OBJECTIVE

To study plasma adiponectin, leptin, IL-8, and hepatocyte growth factor (HGF) in childhood and their independent associations with insulin insensitivity, cross-sectional and in 6-yr prospective.

SUBJECTS

Danish 8- to 10-yr-olds and 14- to 16-yr-olds from the European Youth Heart Studies I and II.

METHODS

Cross-sectional (n = 386) and prospective (n = 246) linear regressions of baseline concentrations of plasma biomarkers and insulin insensitivity at baseline and 6 yr later. Adjustments were made at four progressive steps for sex, sexual maturity, body mass index (BMI), other biomarkers, physical activity, and school location as well as baseline insulin insensitivity in prospective analyses. Insulin insensitivity was measured using homeostasis model assessment standardized to the sample mean [homoestasis model assessment (HOMA) Z-scores]. Plasma biomarkers were quantified using solid-phase protein immunoassays. Overweight was defined as the highest BMI tertile.

RESULTS

Among overweight but not lean children at baseline, one SD difference in baseline plasma adiponectin was associated with -0.41 SD difference in HOMA Z-scores 6 yr later (p = 0.006). At baseline, one SD difference in plasma leptin was associated with 0.36 SD difference in HOMA Z-scores (p =< 0.0001) among 8- to 10-yr-olds, but a prospective association was not found.

CONCLUSIONS

We found a direct relationship between childhood hypo-adiponectinaemia and insulin insensitivity in adolescence. This association was stronger for overweight than for normal weight children. Hyper-leptinaemia was associated with concurrent insulin insensitivity at baseline but not 6 yr later.

Hypoadiponectinemia in overweight children contributes to a negative metabolic risk profile 6 years later

Prognostic biomarkers are needed to identify children at increased cardiometabolic risk. The objective was to study whether markers of metabolism and inflammation, for example, circulating plasma adiponectin, leptin, interleukin-8, and hepatocyte growth factor, are associated with cardiometabolic risk factors in childhood and adolescence. This was a cross-sectional and prospective study, and the setting was the Danish part of the European Youth Heart Studies I and II. Participants were randomly selected girls and boys 8 to 10 years of age with complete baseline data (n = 256) and complete follow-up data 6 years later (n = 169). Cardiometabolic risk profile was calculated using a continuous composite score derived from summing of 6 factors standardized to the sample means (Z scores): body mass index, homeostasis model assessment of insulin resistance, total serum cholesterol to serum high-density lipoprotein cholesterol ratio, serum triglycerides, systolic blood pressure, and the reciprocal value of fitness (maximum watts per kilogram). Overweight was defined using international classification of body mass index cutoff points for children. Plasma adiponectin, leptin, interleukin-8, and hepatocyte growth factor were assessed using immunochemical assays. Linear relationships were found between metabolic risk score and both plasma adiponectin (inverse, P = .02) and plasma leptin (P < .0001) at baseline after adjustment for several confounders. In overweight but not normal-weight children, plasma adiponectin at baseline was inversely associated with metabolic risk score 6 years later (P = .04). In childhood, both hypoadiponectinemia and hyperleptinemia accompany a negative metabolic risk profile. In addition, circulating plasma adiponectin may be a useful biomarker to identify overweight children at greater future risk of the cardiometabolic adverse effects of overweight.

Risk factors for childhood overweight in offspring of type 1 diabetic women with adequate glycemic control during pregnancy: Nationwide follow-up study in the Netherlands

OBJECTIVE

Pregnancy in type 1 diabetic women remains a high-risk situation for both mother and child. In this study, we investigated long-term effects on body composition, prevalence of overweight, and insulin resistance in children of type 1 diabetic women who had had adequate glycemic control during pregnancy (mean A1C 6.2%), and we related their outcome to perinatal factors, including macrosomia (birth weight >90th percentile).

RESEARCH DESIGN AND METHODS

Anthropometric measurements were performed at 6-8 years of age in 213 offspring of type 1 diabetic mothers who participated in a previous nationwide study. Homeostasis model assessment of insulin resistance (HOMA-IR) was determined from a fasting blood sample in 155 of these children. In addition, we studied BMI standard deviation score (SDS) growth trajectories. Results were compared with national reference data.

RESULTS

The prevalence of overweight in the study population was not different from that in the reference population. However, children who were born macrosomic showed twice as much overweight as nonmacrosomic children. Macrosomia and maternal overweight were independent predictors of childhood overweight. Overweight children showed an increase in BMI SDS starting already after 6 months of age and had a significantly increased HOMA-IR.

CONCLUSIONS

In type 1 diabetic women with adequate glycemic control during pregnancy, long-term effects on body composition and overweight in their offspring at school age are limited and related mainly to macrosomia at birth. Possible targets for prevention of childhood overweight are fetal macrosomia, maternal overweight, and an increase in BMI SDS during the first years of life.

Objectively measured physical activity and its association with adiponectin and other novel metabolic markers: a longitudinal study in children (EarlyBird 38)

OBJECTIVE

Recent evidence suggests that, in children, traditional markers of metabolic disturbance are related only weakly to physical activity. We therefore sought to establish the corresponding relationships with newer metabolic markers.

RESEARCH DESIGN AND METHODS

This was a nonintervention longitudinal study of 213 healthy children recruited from 54 schools in Plymouth, U.K. MTI accelerometers were used to make objective 7-day recordings of physical activity at ages 5 +/- 0.3 (mean +/- SD), 6, 7, and 8 years. Overall physical activity was taken as the average of the four annual time points. The metabolic markers at 8 years were adiponectin, leptin, high-sensitivity C-reactive protein (hsCRP), and insulin resistance (homeostasis model assessment). Potential confounders included percent body fat measured by dual-energy X-ray absorptiometry and diet measured by food frequency questionnaire.

RESULTS

Whereas physical activity did not correlate with insulin resistance (r = -0.01), leptin (r = +0.04), or hsCRP (r = +0.01) independently of percent body fat, it did correlate with adiponectin, but inversely (r = -0.18, P = 0.02). This unexpected inverse relationship was strongest among the less active children (physical activity < median: r = -0.30, P = 0.01) but negligible in the more active children (physical activity > median: r = +0.04, P = 0.76). Adiponectin was significantly higher (0.52 SD, P < 0.01) in the least active tertile compared with the other two tertiles. Insulin resistance, however, did not differ across the physical activity tertiles (P = 0.62).

CONCLUSIONS

Adiponectin levels in children are highest among those who are least active, but their insulin resistance is no different. Adiponectin has a known insulin-sensitizing effect, and our findings are consistent with a selective effect at low levels of physical activity.