Pubertal alterations in growth and body composition. VI. Pubertal insulin resistance: relation to adiposity, body fat distribution and hormone release

Trends in HOMA-IR values among South Korean adolescents from 2007-2010 to 2019-2020: a sex-, age-, and weight status-specific analysis

BACKGROUND/OBJECTIVES

An increase in obesity prevalence may lead to an increase in the HOMA-IR value. This study aimed to investigate changes in age- and sex-specific homeostasis model assessment of insulin resistance (HOMA-IR) values among South Korean adolescents, using data from the Korean National Health and Nutrition Examination Survey (KNHANES) IV, V, and VIII conducted between 2007-2010 and 2019-2020.

SUBJECTS/METHODS

Overall, 4621 adolescents aged 10-18 years were evaluated, including 3473 from the 2007-2010 dataset and 1148 from the 2019-2020 dataset. The mean HOMA-IR values and percentile curves were evaluated by age, sex, and weight status.

RESULTS

The mean HOMA-IR values peaked at puberty in both sexes and further increased during puberty in the 2019-2020 dataset (boys 5.21, 95% confidence interval [CI] 4.16-6.26; girls 5.21, 95% CI 3.09-7.33) compared with the 2007-2010 dataset (boys 3.25, 95% CI 3.04-3.47; girls 3.58, 95% CI 3.31-3.85). Both groups (with normal-weight and overweight/obesity) exhibited a peak HOMA-IR value during puberty in both sexes and both datasets, although the group with overweight/obesity had a higher and wider peak age range. While the mean HOMA-IR values did not change in adolescents with normal-weight, they increased during puberty and post-puberty in boys with overweight/obesity.

CONCLUSIONS

HOMA-IR values should be interpreted considering sex, weight status, and pubertal stages. In particular, during the pubertal period, insulin resistance (IR) can coexist not only due to weight-related factors but also as a result of the distinct hormonal changes characteristic of puberty. Over the 10-year period, the mean HOMA-IR values increased in the group with overweight/obesity during puberty and post-puberty, highlighting the need for active intervention to prevent metabolic complications in adolescents with overweight/obesity.

Enhancing cardiometabolic health through physical activity and breakfast manipulations in children and adolescents: good for humans, good for the planet

The human health benefits of cardiometabolic disease prevention can be accompanied by planetary co-benefits. Focusing efforts towards young people, including children and adolescents, is conducive to disease prevention. In the context of cardiometabolic disease prevention, this review paper critically summarises the available literature on the acute cardiometabolic responses to physical activity and breakfast manipulations among young people. Given the seriousness of global climate change, which will disproportionally affect our younger generations, this review paper offers new insights into the inherent interactions between child-adolescent behaviour and cardiometabolic health from an environmental sustainability perspective to aid climate change mitigation efforts, including exploring future research avenues. A growing evidence base suggests acute moderate- to high-intensity exercise bouts can attenuate postprandial plasma glucose, insulin and triacylglycerol concentrations for up to 24-48 h in young people. Whether accumulating physical activity throughout the day with short, frequent bouts promotes cardiometabolic risk marker attenuations is unclear. Breakfast consumption may enhance free-living physical activity and reduce glycaemic responses to subsequent meals for a possible additive impact. If repeated habitually, attenuations in these cardiometabolic risk factors would be conducive to disease prevention, reducing the greenhouse gas emissions associated with disease diagnosis and treatment. To progress current understanding with high public health and planetary relevance, research among samples of 'at risk' young people that span cellular-level responses to ecologically valid settings and address human and planetary health co-benefits is needed. Indeed, certain physical activity opportunities, such as active travel to school, offer important direct co-benefits to humans and planetary health.

Youth-Onset Type 2 Diabetes: The Epidemiology of an Awakening Epidemic

In this narrative review, we describe the epidemiology (prevalence, incidence, temporal trends, and projections) of type 2 diabetes among children and adolescents (<20 years), focusing on data from the U.S. and reporting global estimates where available. Secondarily, we discuss the clinical course of youth-onset type 2 diabetes, from prediabetes to complications and comorbidities, drawing comparisons with youth type 1 diabetes to highlight the aggressive course of this condition, which, only recently, has become recognized as a pediatric disease by health care providers. Finally, we end with an overview of emerging topics in type 2 diabetes research that have potential to inform strategies for effective preventive action at the community and individual levels.

Youth versus adult-onset type 2 diabetic kidney disease: Insights into currently known structural differences and the potential underlying mechanisms

Type 2 diabetes (T2D) is a global health pandemic with significant humanitarian, economic, and societal implications, particularly for youth and young adults who are experiencing an exponential rise in incident disease. Youth-onset T2D has a more aggressive phenotype than adult-onset T2D, and this translates to important differences in rates of progression of diabetic kidney disease (DKD). We hypothesize that youth-onset DKD due to T2D may exhibit morphometric, metabolic, and molecular characteristics that are distinct from adult-onset T2D and develop secondary to inherent differences in renal energy expenditure and substrate metabolism, resulting in a central metabolic imbalance. Kidney structural changes that are evident at the onset of puberty also serve to exacerbate the organ’s baseline high rates of energy expenditure. Additionally, the physiologic state of insulin resistance seen during puberty increases the risk for kidney disease and is exacerbated by both concurrent diabetes and obesity. A metabolic mismatch in renal energetics may represent a novel target for pharmacologic intervention, both for prevention and treatment of DKD. Further investigation into the underlying molecular mechanisms resulting in DKD in youth-onset T2D using metabolomics and RNA sequencing of kidney tissue obtained at biopsy is necessary to expand our understanding of early DKD and potential targets for therapeutic intervention. Furthermore, large-scale clinical trials evaluating the duration of kidney protective effects of pharmacologic interventions that target a metabolic mismatch in kidney energy expenditure are needed to help mitigate the risk of DKD in youth-onset T2D.

The Relationship between Fat Mass Percentage and Glucose Metabolism in Children and Adolescents: A Systematic Review and Meta-Analysis

To assess the relationship between fat mass percentage (FMP) and glucose metabolism in children aged 0−18 years we performed a systematic review of the literature on Medline/PubMed, SinoMed, Embase and Cochrane Library using the PRISMA 2020 guidelines up to 12 October 2021 for observational studies that assessed the relationship of FMP and glucose metabolism. Twenty studies with 18,576 individuals were included in the meta-analysis. The results showed that FMP was significantly associated with fasting plasma glucose (FPG) (r = 0.08, 95% confidence interval (CI): 0.04−0.13, p < 0.001), fasting plasma insulin (INS) (r = 0.48, 95% CI: 0.37−0.57, p < 0.001), and homeostasis model assessment (HOMA)- insulin resistance (IR) (r = 0.44, 95% CI: 0.33−0.53, p < 0.001). The subgroup analysis according to country or overweight and obesity indicated that these associations remained significant between FMP and INS or HOMA-IR. Our results demonstrated that there is a positive relationship between FMP and FPG. Moreover, subgroup analysis according to country or overweight and obesity indicated that FMP is significantly associated with INS and HOMA-IR. This is the first known systematic review and meta-analysis to determine the associations of FMP with glucose metabolism in children and adolescents.

Diurnal Variation of Real-Life Insulin Sensitivity Factor Among Children and Adolescents With Type 1 Diabetes Using Ultra-Long-Acting Basal Insulin Analogs

BACKGROUND

Estimation of insulin sensitivity factor (ISF) is essential for correction insulin doses calculation. This study aimed to assess real-life ISF among children and adolescents with type 1 diabetes using ultra-long-acting basal insulin analogs and to detect factors associated with ISF among those patients.

METHODS

This prospective observational study was conducted at Sohag University Hospital, Egypt, and included 93 participants aged 6-18 years, diagnosed with T1DM for at least 1 year and using insulin glargine 300 Units/mL or insulin degludec 100 Units/mL as basal insulin. The ISF, insulin-to-carbohydrate ratio (ICR) and insulin doses were initially assessed then adjusted as required. The participants were regularly contacted throughout the follow-up period. Glycemic control parameters were assessed after 3 months.

RESULTS

The ISF showed diurnal variation with higher correction dose requirements for the morning than for the rest of the day (p < 0.001). This pattern of diurnal variation was found in participants with different pubertal stages and in participants using either type of ultra-long acting basal insulin analogs. There was no significant difference between the ISF calculated according to the 1800 rule [1800/Total daily insulin dose (TDD)] and the morning ISF (p = 0.25). The 1800 rule-calculated ISF was significantly lower than the actual ISF for the afternoon (p < 0.001) and the evening (p < 0.001). ISF at different times of the day were significantly correlated with age, body mass index, pubertal stage, diabetes duration, TDD, and ICR. Multiple regression analysis revealed that ICR was the most significant factor associated with ISF. Linear regression analysis revealed that the ISF (in mg/dL) for any time of the day could be estimated as 5.14 × ICR for the same time of the day (coefficient = 5.14, 95% confidence interval: 5.10-5.19, R ² = 0.95, p < 0.001).

CONCLUSION

Diurnal variation of ISF that had to be considered for proper calculation of correction doses. This diurnal variation was found in children and adolescents with different pubertal stages. The 1800 rule was appropriate for the morning correction doses but not in the afternoon or the evening. The TDD and the ICR could be used for ISF estimation.

Insulin-like growth factor-1 status is associated with insulin resistance in young patients with spinal muscular atrophy

Insulin-like growth factor-1 (IGF-1) is an anabolic hormone with myotrophic effects on muscle tissue. Patients with spinal muscular atrophy (SMA) sustain early-onset sarcopenia, which contributes to an increased prevalence of insulin resistance. Our aim was to determine the IGF-1 status in 5q-SMA patients and its association with insulin resistance. Real-life clinical and laboratory data of 34 patients (15 males; age 3 months-24 years) included: anthropometric measurements [weight, height/length, body mass index or weight-to-length ratio, delta-height standard deviation score (∆Ht SDS) as the difference between height/length SDS and mid-parental height (MPHt) SDS] and laboratory measurements [Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and IGF-1]. HOMA-IR levels categorized patients as insulin-resistant [HOMA-IR ≥1.9 (n = 20)] or insulin-sensitive [HOMA-IR <1.9 (n = 14)]. The collective height/length SDS was -0.29±1.34 and ∆Ht SDS was -0.11±1.47. IGF-1 levels were within the normal population range for all patients. Insulin-resistant patients had higher IGF-1 SDS levels compared to insulin-sensitive patients (0.87±0.78 vs. -0.67±0.96, respectively, P<0.001). The IGF-1 SDS was significantly associated with HOMA-IR for all subjects (r = 0.547, P = 0.001), and linear growth parameters (height/length SDS, ∆Ht SDS) were significantly associated with IGF-1 SDS in the insulin-resistant subgroup (r = 0.649, P = 0.002 and r = 0.605, P = 0.005, respectively). Our findings suggest that IGF-1 status is associated with insulin resistance in patients with early-onset sarcopenia.

The Impact of Obesity On Insulin Sensitivity and Secretion During Pubertal Progression: A Longitudinal Study

CONTEXT

Physiologic changes in glucose metabolism are well-described to occur during puberty. However, there are important gaps in understanding the interaction between obesity and the normal physiologic changes during puberty, as well as how these changes could contribute to the increased risk of comorbidities, such as type 2 diabetes and dyslipidemia, in youth with obesity.

OBJECTIVE

The objective of this study was to compare longitudinal changes in insulin sensitivity (Si) and secretion during pubertal progression in youth with obesity versus those with normal weight.

DESIGN

Longitudinal observational study evaluating youth from early puberty (Tanner [T]2-T3) until puberty completion (T5).

SETTING

Pediatric academic hospital Clinical Translational Research Center.

PARTICIPANTS

Pubertal youth with normal weight (n = 47; 22 female, 25 male) and obesity (n = 37; 23 female, 14 male).

MAIN OUTCOME MEASURES

Si, insulin response (acute insulin response to glucose, AIRg) and disposition index (DI) by intravenous glucose tolerance test at baseline (T2-T3), T4, and T5.

RESULTS

Youth with obesity had significantly lower Si and higher AIRg at each time point (P < 0.001), but DI was similar between the groups. There were no group differences in trajectory of Si, AIRg or DI over time. Leptin, insulin-like growth factor-1, and obesity were most strongly associated with Si and AIRg at all time points.

CONCLUSIONS

Obesity significantly impacts Si during puberty, even at the earliest stages. However, in general, obese youth have adequate β-cell compensation for the significantly reduced Si of puberty. Future studies are needed to better predict the subset of youth who fail to maintain β-cell compensation during puberty.

Branched-Chain and Aromatic Amino Acids Are Associated With Insulin Resistance During Pubertal Development in Girls

PURPOSE

Cross-sectional studies in children show branched-chain and aromatic amino acids are associated with insulin resistance, but whether these associations persist from childhood to adulthood is not known. This study aimed to assess whether circulating amino acids associate with insulin resistance during pubertal development.

METHODS

This was a 7.5-year longitudinal study from childhood to early adulthood. A total of 396 nondiabetic Finnish girls aged 11.2 ± .8 years at baseline participated in the study which was conducted at the Health Science Laboratory, University of Jyväskylä. Serum concentrations of glucose and insulin were determined by enzymatic photometric methods and amino acids by nuclear magnetic resonance spectroscopy. Insulin resistance was determined by the homeostatic model assessment of insulin resistance (HOMA-IR).

RESULTS

All amino acids were positively associated with HOMA-IR both before and after menarche (p < .05 for all), except for histidine. Branched-chain amino acids and aromatic amino acids showed the strongest associations, the magnitude of correlation coefficients being similar before and after menarche (R² = .064-.171). After adjusting for body mass index z-score and height, the associations between branched-chain amino acids and aromatic amino acids and HOMA-IR remained significant both before and after menarche.

CONCLUSIONS

Branched-chain amino acids and aromatic amino acids associate with insulin resistance during pubertal development, independent of adiposity. Further studies are needed to determine whether changes in amino acid metabolism link pubertal hyperinsulinemia to accelerated physiological growth and/or heightened cardiometabolic risk later in life.

Acanthosis nigricans as a clinical marker of insulin resistance among overweight adolescents

PURPOSE

Acanthosis nigricans (AN) is a hyperpigmented dermatosis associated with obesity and insulin resistance (IR). There is no consensus whether AN extension scoring offers added value to the clinical estimation of IR. In this study we aimed to assess and score AN using both a short and an extended version of the scale proposed by Burke et al. and analyze the relationships of both versions with hyperinsulinemia and IR.

METHODS

We analyzed data from 139 overweight adolescents (body mass index ≥85th percentile) aged 12-18 with (n=67) or without (n=72) AN who were followed at a pediatric obesity clinic.

RESULTS

Adolescents with AN had higher levels of insulin (d=0.56, P=0.003) and HOMA-IR (d=0.55, P=0.003) compared to those without. Neither the short nor the extended versions of AN scores explained either hyperinsulinemia (β=1.10, P=0.316; β=1.15, P=0.251) or IR (β=1.07, P=0.422; β=1.10, P=0.374). The presence of AN alone predicted hyperinsulinemia and the presence of IR in 7.3% (β=2.68, P=0.008) and 7.1% (β=2.59, P=0.009) of adolescents, respectively.

CONCLUSION

Screening for AN at the neck and axilla is a noninvasive and cost-effective way to identify asymptomatic overweight adolescents with or at risk of developing IR.

Does sex hormone-binding globulin cause insulin resistance during pubertal growth?

BACKGROUND

The directional influences between serum sex hormone-binding globulin (SHBG), adiposity and insulin resistance during pubertal growth remain unclear. The aim of this study was to investigate bidirectional associations between SHBG and insulin resistance (HOMA-IR) and adiposity from childhood to early adulthood.

METHODS

Participants were 396 healthy girls measured at baseline (age 11.2 years) and at 1, 2, 4 and 7.5 years. Serum concentrations of estradiol, testosterone and SHBG were determined by ELISA, glucose and insulin by enzymatic photometry, insulin-like growth factor 1 (IGF-1) by time-resolved fluoroimmunoassays, whole-body fat mass by dual-energy X-ray absorptiometry and HOMA-IR were determined by homeostatic model assessment. The associations were examined using cross-lagged path models.

RESULTS

In a cross-lagged path model, SHBG predicted HOMA-IR before menarche β = -0.320 (95% CI: -0.552 to -0.089), P = 0.007, independent of adiposity and IGF-1. After menarche, no directional effect was found between SHBG and insulin resistance or adiposity.

CONCLUSIONS

Our results suggest that in early puberty, decline in SHBG predicts development of insulin resistance, independent of adiposity. However, after menarche, no directional influences between SHBG, adiposity and insulin resistance were found, suggesting that observational associations between SHBG, adiposity and insulin resistance in pubertal children may be subject to confounding. Further research is needed to understand the underlying mechanisms of the associations between SHBG and cardiometabolic risk markers in peripubertal children.

Metabolic trajectories across early adolescence: differences by sex, weight, pubertal status and race/ethnicity

Background: Biomarkers of cardiovascular and metabolic risk track from adolescence into adulthood, therefore characterising the direction and magnitude of these changes is an important first step to identifying health trajectories that presage future disease risk.Aim: To characterise changes in metabolic biomarkers across early adolescence in a multi-ethnic cohort.Subjects and methods: Among 891 participants in Project Viva we estimated changes in insulin resistance (HOMA-IR), adipokines, lipids, and SBP between ages 6-10 years and 11-16 years. Next, we used multivariable linear regression to examine associations of sex, baseline overweight/obesity, baseline pubertal status and race/ethnicity with change in the biomarkers during follow-up.Results: Boys exhibited a larger decrement in adiponectin (-0.66 [95% CI = -1.14, -0.18)] ng/mL) and a greater increase in SBP (3.20 [2.10, 4.30] mmHg) than girls. Overweight/obese participants experienced larger increases in HOMA-IR, leptin, and triglycerides; and a steeper decrement in HDL. Pubertal youth showed larger decrements in total and LDL cholesterol than their pre-pubertal counterparts. In comparison to White participants, Black youth experienced a larger magnitude of increase in HOMA-IR, and Hispanic youth exhibited larger decrements in adiponectin and HDL.Conclusions: Change in metabolic biomarkers across early adolescence differed by sex, weight status, pubertal status and race/ethnicity. Some of the metabolic changes may reflect normal physiological changes of puberty, while others may presage future disease risk. Future studies are warranted to link metabolic changes during adolescence to long-term health.

Current treatment options for acanthosis nigricans

Acanthosis nigricans (AN) is a common dermatologic manifestation of systemic disease that is associated with insulin resistance, diabetes mellitus, obesity, internal malignancy, endocrine disorders, and drug reactions. Treatment of AN primarily focuses on resolution of the underlying disease processes causing the velvety, hyperpigmented, hyperkeratotic plaques found on the skin. While the goal of therapy is to treat the primary cause, cosmetic resolution of AN lesions can be important for patients and their quality of life. Treatment options for AN have not been extensively studied; however, smaller powered clinical trials and case reports exist in the literature. Our review aims to explore and evaluate the current treatment options that exist for AN.

DXA-measured visceral fat mass and lean body mass reflect abnormal metabolic phenotypes among some obese and nonobese Chinese children and adolescents

BACKGROUND AND AIM

The exact constellation of body composition characteristics among metabolically unhealthy obese (MUO) and nonobese (MUNO) children and adolescents remains unclear. The purpose of this study was to identify the major body composition determinants of metabolically unhealthy phenotypes among Chinese children and adolescents.

METHODS AND RESULTS

We used data from a cross-sectional survey in 2015 that included 1983 children and adolescents aged 6-18 years. Subjects were classified into two phenotypes based on a combination of body mass index (BMI) and metabolic syndrome components. Body composition was measured by dual-energy X-ray absorptiometry (DXA). Among all boys and among adolescent boys, those with MUNO phenotypes displayed significantly higher indices of body composition except for fat mass (FM) percentage and trunk-to-legs FM ratio compared with the metabolically healthy nonobese phenotype (all P < 0.05). MUO individuals had higher arm FM, lean body mass (LBM), and trunk lean mass compared to metabolically healthy obese individuals (all P < 0.05). Visceral fat mass (VFM) and BMI were the major independent determinants of MUNO (VFM, 6- to 9-year-old boys, OR = 1.02, 95% CI = 1.00-1.03, P = 0.021; BMI, 6- to 9-year-old girls, OR = 1.90, 95% CI = 1.31-2.84, P = 0.001; and adolescent boys, OR = 1.34, 95% CI = 1.23-1.44, P < 0.001). LBM was the major independent predictor of MUO among adolescent boys (OR = 1.90, 95% CI = 1.03-1.17, P = 0.003).

CONCLUSIONS

Among children and adolescents, the metabolically unhealthy phenotype was associated with excess of body composition, but with significant differences observed based on age and sex. VFM and LBM derived by DXA can predict the metabolically unhealthy phenotype effectively in specific sex and age groups.

Higher phthalate concentrations are associated with precocious puberty in normal weight Thai girls

BACKGROUND

The cause of precocious puberty may be associated with genetics and other conditions such as central nervous system (CNS) insults, or the exposure to endocrine disrupting chemicals (EDCs). Phthalates is known to be one of the EDCs and have estrogenic and antiandrogenic activities, and may be associated with advanced puberty. The objective of the study was to determine the association between urinary phthalate metabolites and advanced puberty.

METHODS

A cross-sectional study was conducted in patients with precocious puberty (breast onset <8 years, n=42) and early puberty (breast onset 8-9 years, n=17), compared to age-matched controls (n=77). Anthropometric measurements, estradiol, basal and gonadotropin releasing hormone (GnRH)-stimulated follicle stimulating hormone (FSH) and luteinizing hormone (LH) levels, uterine sizes, ovarian diameters and bone ages (BA) were obtained. Urine samples were collected and mono-methyl phthalate (MMP) and mono-ethyl phthalate (MEP) were analyzed by high performance liquid chromatography (HPLC) and adjusted with urine creatinine.

RESULTS

The median adjusted-MEP concentration in girls with precocious puberty, was greater than in normal girls (6105.09 vs. 4633.98 μg/g Cr: p<0.05), and had the same trend among early puberty and normal puberty (5141.41 vs. 4633.98 μg/g Cr: p=0.4), but was not statistically significant.

CONCLUSIONS

Precocious puberty girls had an association with increased MEP concentration. This is the first report of the association between urinary phthalate levels and precocious puberty in Thai girls.

Increased levels of bisphenol A (BPA) in Thai girls with precocious puberty

BACKGROUND

Reports on the secular trend of pubertal onset indicate a recent earlier start especially in girls. Bisphenol A (BPA), which posses estrogenic activity, might be a cause of advanced puberty. The objective of the study was to determine the association between BPA and advanced puberty.

METHODS

A cross-sectional study was conducted in patients with advanced puberty (n=41) compared to age-matched controls (n=47). Anthropometric measurements, estradiol, basal and gonadotropin releasing hormone (GnRH)-stimulated follicle stimulating hormone (FSH) and luteinizing hormone (LH) levels, uterine sizes, ovarian diameters and bone ages were obtained. Urinary BPA concentrations were analyzed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC/MSMS) with the lower limit of quantification (LLOQ) of 0.05 ng/mL.

RESULTS

The median adjust-BPA concentration in advanced puberty group was higher than in control groups [1.44 vs. 0.59 μg/g creatinine (Cr): p<0.05]. We also found that the median adjust-BPA concentration in girls with advanced puberty who were overweight/obese, was greater than in the normal pubertal overweight/obese girls (1.74 vs. 0.59 μg/g Cr: p<0.05), and was in the same trend among normal weight girls with advanced and normal puberty (0.83 vs. 0.49 μg/g Cr: p=0.09), but not statistically significant.

CONCLUSIONS

The present findings suggest that BPA exposure appears to be related to an earlier age at onset of puberty especially in obese girls.

Progression from impaired glucose tolerance to type 2 diabetes in obese children and adolescents: a 3-6-year cohort study in southern Thailand

BACKGROUND

Childhood obesity is associated with abnormal glucose metabolism and type 2 diabetes mellitus (T2DM). This study evaluated the prevalence of abnormal glucose metabolism in asymptomatic obese children and adolescents, and determined the percentage of T2DM development after 3-6 years of follow-up.

METHODS

During 2007-2013, 177 obese children and adolescents who had normal fasting plasma glucose (FPG<100 mg/dL) were given an oral glucose tolerance test (OGTT). The participants were classified into four groups: normal glucose tolerance (NGT), NGT-hyperinsulinemia (NGT-HI), impaired glucose tolerance (IGT), and diabetes mellitus (DM). Blood chemistries, including FPG, glycated hemoglobin, and lipid profiles, and liver function test were performed every 6-12 months or when the patient developed any symptom or sign indicative of diabetes.

RESULTS

Glucose metabolism alterations were detected in 81.4% of the participants: 63.8% with NGT-HI, 15.3% with IGT, and 2.3% with T2DM. The median levels of homeostasis model assessment-insulin resistance (HOMA-IR) in patients with IGT (8.63) were significantly greater than those in the patients with NGT (4.04) (p<0.01). During the follow-up, 22 patients (14.4%) developed T2DM significantly more from the IGT group (nine of 33 cases, 27.3%) than the NGT-HI group (12 of 108 cases, 11.1%) (p=0.022). The predicting parameters for T2DM conversion were weight status, body mass index (BMI), FBG, fasting insulin, alanine transaminase (ALT) levels, and HOMA-IR.

CONCLUSIONS

Glucose metabolism alteration was commonly found among obese adolescents. Factors associated with T2DM development were greater weight status and the severity of insulin resistance as shown by higher HOMA-IR levels.

Comparisons of physical activity, adipokines, vitamin D status and dietary vitamin D intake among adolescents

BACKGROUND

Considering that lifestyle and diet are key factors responsible for the increases in adiposity in youth, it is important to understand how vitamin D, adipokines and markers of glucose metabolism are related to physical activity level (PAL) during growth. The present study aimed to investigate associations between physical activity level, adiponectin/leptin ratio, vitamin D status and dietary vitamin D intake among adolescents.

METHODS

A cross-sectional study was conducted with adolescents aged 14-18 years old who were living in São Paulo, Brazil. Serum 25 hydroxyvitamin D [25(OH)D], adiponectin (A), leptin (L), glucose and insulin were obtained after 12 h of fasting. Dietary calcium and vitamin D intake were measured by 24-h food record, as repeated in 62.6% of the sample. PAL was measured by the International Physical Activity Questionnaire (IPAQ). Pearson's chi-square test, Pearson correlation and linear regression analysis were performed.

RESULTS

A total of 198 subjects, mean (SD) age 16.3 (1.4) years, 51% male, were enrolled in the study. Some 9% of participants were sedentary, 22% were insufficiently active (IA), 51% were active and 18% were very active (VA). The A/L ratio was lower among sedentary/IA subjects [2.2 (4.0) versus 5.6 (12.3); P = 0.01] compared to active/VA subjects. PAL was not associated with vitamin D status or markers of glucose metabolism. Serum 25(OH)D positively associated with vitamin D intake, after adjusting for sex, sun exposure and season of the year in regression analysis (partial r² =0.026, P = 0.02).

CONCLUSIONS

Low PAL was associated with a lower A/L ratio. Vitamin D status was not associated with sun exposure habits, although it was positively correlated with vitamin D intake.

Beta-cell function and insulin resistance among Peruvian adolescents with type 2 diabetes

OBJECTIVE

To characterize and compare the beta-cell function and insulin resistance among Peruvian adolescents with type 2 diabetes (T2D) and their non-diabetic, overweight and lean peers.

METHODS

Cross-sectional study of 54 adolescents aged 10-19 years, distributed in three sex- and age-matched groups (n = 18): (i) adolescents with T2D; (ii) overweight adolescents without T2D; and (iii) lean adolescents without T2D, at the Diabetes, Obesity and Nutrition Research Center in Lima, Peru. Fasting glucose, insulin, C-peptide, and glycated hemoglobin were measured for all participants. In addition, a two-hour oral glucose tolerance test (OGTT, 1.75 mg of glucose/kg body weight) was performed, during which glucose and C-peptide were quantified. The homeostasis model assessment of insulin resistance (HOMA-IR) and beta-cell function (HOMA-B) were derived for all participants, and beta-cell function was further examined by the area under the curve (AUC) of C-peptide.

RESULTS

The median HOMA-IR score was higher in adolescents with T2D compared to lean adolescents (6.1 vs. 2.1; p = 0.002), but was not different from that of overweight adolescents (6.1 vs. 4.0; p = 0.322). The median HOMA-B was higher in overweight adolescents than in lean adolescents (256.9 vs. 134.2; p = 0.015), and adolescents with T2D (256.9 vs. 119.8; p = 0.011). The mean AUC of glucose in adolescents with T2D was 1.8-fold higher than that of overweight adolescents, and 1.9-fold higher than that of lean adolescents (p < 0.001). Although the median AUC of C-peptide in adolescents with T2D was lower than that of overweight and lean adolescents, this difference was not statistically significant (230.7 vs. 336.6 vs. 267.3 nmol/l120 min, respectively; p = 0.215).

CONCLUSION

Among Peruvian adolescents with T2D, insulin resistance is the most prominent characteristic, rather than beta-cell dysfunction.

Insulin Resistance of Puberty

Puberty is a time of considerable metabolic and hormonal change. Notably, puberty is associated with a marked decrease in insulin sensitivity, on par with that seen during pregnancy. In otherwise healthy youth, there is a nadir in insulin sensitivity in mid-puberty, and then it recovers at puberty completion. However, there is evidence that insulin resistance (IR) does not resolve in youth who are obese going into puberty and may result in increased cardiometabolic risk. Little is known about the underlying pathophysiology of IR in puberty, and how it might contribute to increased disease risk (e.g., type 2 diabetes). In this review, we have outlined what is known about the IR in puberty in terms of pattern, potential underlying mechanisms and other mediating factors. We also outline other potentially related metabolic changes that occur during puberty, and effects of underlying insulin resistant states (e.g., obesity) on pubertal changes in insulin sensitivity.

Elevated blood pressure in adolescent girls: correlation to body size and composition

Background

To improve understanding of the pathophysiology of hypertension in adolescents and pave the way for risk stratification, studies have sought to determine the correlates of blood pressure (BP). Inconsistencies in dependent and independent variables have resulted in an elusive consensus. The aim of this report is to examine an inclusive array of correlates of BP, as a continuous (systolic and diastolic BP) and a dichotomous variable.

Methods

Subjects were a school-based sample of 730 urban, mostly African American, non-referred 6th and 7th grade girls. To find independent correlates of SBP/DBP, we used a stepwise model selection method based on the Schwarz Bayesian Information Criterion, enabling selection of a parsimonious model among highly correlated covariates. Candidate variables were: age, stature, heart rate, pubertal development, BMI, BMI z-score, waist circumference, waist-to-height ratio (WHtR), body surface area, fat mass (by bioelectrical impedance analysis), fat-free mass (FFM), percentage of body fat, and presence of overweight/obesity.

Results

The best-fitting models for DBP and SBP (considered separately) included fat-free mass, heart rate and, in the case of SBP, stature. The best-fitting model for high-normal/elevated blood pressure (H-N/EBP) included WHtR with no independent relation of any other variable. The prevalence of H-N/EBP tripled between a WHtR of 0.5 and 0.7.

Conclusions

The easily obtained and calculated WHtR is the strongest correlate of elevated blood pressure among available variables and is a prime candidate for longitudinal studies of predictors of the development of hypertension.

Trial registration

ClinicalTrials.gov Identifier, NCT00746083

Change in HbA1c levels between the age of 8 years and the age of 12 years in Dutch children without diabetes: the PIAMA birth cohort study

OBJECTIVE

HbA1c is associated with cardiovascular risk in persons without diabetes and cardiovascular risk accumulates over the life course. Therefore, insight in factors determining HbA1c from childhood onwards is important. We investigated (lifestyle) determinants of HbA1c at age 12 years and the effects of growth on change in HbA1c and the tracking of HbA1c between the age of 8 and 12 years.

STUDY DESIGN AND METHODS

Anthropometric measurements were taken and HbA1c levels were assessed in 955 children without diabetes aged around 12 years participating in the PIAMA birth cohort study. In 363 of these children HbA1c was also measured at age 8 years. Data on parents and children were collected prospectively by questionnaires.

RESULTS

We found no significant association between known risk factors for diabetes and HbA1c at age 12 years. Mean(SD) change in HbA1c between ages 8 and 12 years was 0.6(0.7) mmol/mol per year (or 0.1(0.1) %/yr). Anthropometric measures at age 8 and their change between age 8 and 12 years were not associated with the change in HbA1c. 68.9% of the children remained in the same quintile or had an HbA1c one quintile higher or lower at age 8 years compared to age 12 years.

CONCLUSION

The lack of association between known risk factors for diabetes and HbA1c suggest that HbA1c in children without diabetes is relatively unaffected by factors associated with glycaemia. HbA1c at age 8 years is by far the most important predictor of HbA1c at age 12. Therefore, the ranking of HbA1c levels appear to be fairly stable over time.

At the crossroad between obesity and gastric cancer

Obesity has reached epidemic proportions worldwide with disproportionate prevalence in different communities and ethnic groups. Recently, the American Medical Association recognized obesity as a disease, which is a significant milestone that opens the possibilities of treating obesity under standardized health plans. Obesity is an inflammatory disease characterized by elevated levels of biomarkers associated with abnormal lipid profiles, glucose levels, and blood pressure that lead to the onset of metabolic syndrome. Interestingly, inflammatory biomarkers, in particular, have been implicated in the risk of developing several types of cancer. Likewise, obesity has been linked to esophageal, breast, gallbladder, kidney, pancreatic, and colorectal cancers. Thus, there exists a link between obesity status and tumor appearance, which may be associated to the differential levels and the circulating profiles of several inflammatory molecules. For example, mediators of the inflammatory responses in both obesity and gastric cancer risk are the same: pro-inflammatory molecules produced by the activated cells infiltrating the inflamed tissues. These molecules trigger pathways of activation shared by obesity and cancer. Therefore, understanding how these different pathways are modulated would help reduce the impact that both diseases, and their concomitant existence, have on society.

Metabolic syndrome in overweight and obese adolescents: a comparison of two different diagnostic criteria

BACKGROUND

Due to the lack of consensus on its definition, the metabolic syndrome (MS) in children and adolescents is not formally recognized. However, several researchers have changed the adult criteria for pediatric standards in order to assess the prevalence.

OBJECTIVE

The aim of this study was to evaluate the frequency of MS and its components according to two of the currently used definitions in overweight and obese adolescents.

METHODS

A cross-sectional study with 232 adolescents with excess weight from a public school of the city of Rio de Janeiro. Anthropometric, blood pressure, and biochemical variables were assessed. MS was defined using two different diagnostic criteria: the National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATPIII) and International Diabetes Federation (IDF).

RESULTS

MS was diagnosed in 40.4 and 24.6% of obese adolescents and 9.4 and 1.9% of overweight adolescents according to the NCEP-ATPIII and IDF criteria, respectively. The degree of agreement, assessed by the κ index, from the definitions adopted in this study was 0.48.

CONCLUSION

The results show a significant difference between the two diagnostic criteria. A higher frequency was found when the NCEP-ATPIII was used, which is of concern given the association of MS with diabetes and cardiovascular disease.

Relationships of body composition and liver fat content with insulin resistance in obesity-matched adolescents and adults

OBJECTIVE

While in adults not total body- or visceral fat mass, but liver fat content was found to independently determine insulin resistance, it is unclear whether these relationships are already present in obese adolescents.

METHODS

Thirty-nine overweight/obese adolescents were matched for sex and BMI with 39 adults. To compare the age- and sex-specific BMI values of adolescents and adults, the percentile value of each adolescent was projected to the age of 18. Body fat depots were quantified by whole-body magnetic resonance (MR) imaging. Liver fat content was measured with (1)H-MR spectroscopy. Insulin resistance was estimated from the homeostasis model assessment of insulin resistance (HOMA-IR).

RESULTS

Compared to overweight and obese adults, adolescents had higher HOMA-IR (P < 0.001) and lower lean body mass (P = 0.002). Furthermore, they had higher total body- (P = 0.02), but lower visceral- (P < 0.001) fat mass, while liver fat content was not significantly different between the groups (P = 0.16). In both groups liver fat content (both P ≤ 0.007), but not total body- or visceral fat mass (all P ≥ 0.64) was an independent predictor of insulin resistance.

CONCLUSIONS

Having lower visceral fat mass, overweight and obese adolescents are more insulin resistant than sex- and BMI-matched adults. Liver fat content, but not total body- or visceral fat mass, is an independent determinant of insulin resistance in adolescents.

Childhood obesity and its impact on the development of adolescent PCOS

Obesity exacerbates the reproductive and metabolic manifestations of polycystic ovary syndrome (PCOS). The symptoms of PCOS often begin in adolescence, and the rising prevalence of peripubertal obesity has prompted concern that the prevalence and severity of adolescent PCOS is increasing in parallel. Recent data have disclosed a high prevalence of hyperandrogenemia among peripubertal adolescents with obesity, suggesting that such girls are indeed at risk for developing PCOS. Obesity may impact the risk of PCOS via insulin resistance and compensatory hyperinsulinemia, which augments ovarian/adrenal androgen production and suppresses sex hormone-binding globulin (SHBG), thereby increasing androgen bioavailability. Altered luteinizing hormone (LH) secretion plays an important role in the pathophysiology of PCOS, and although obesity is generally associated with relative reductions of LH, higher LH appears to be the best predictor of increased free testosterone among peripubertal girls with obesity. Other potential mechanisms of obesity-associated hyperandrogenemia include enhanced androgen production in an expanded fat mass and potential effects of abnormal adipokine/cytokine levels. Adolescents with PCOS are at risk for comorbidities such as metabolic syndrome and impaired glucose tolerance, and concomitant obesity compounds these risks. For all of these reasons, weight loss represents an important therapeutic target in obese adolescents with PCOS.

Parasympathetic cardiac activity is associated with cardiorespiratory fitness in overweight and obese adolescents

The aim of this study was to investigate the association between cardiac parasympathetic activity and cardiorespiratory fitness, insulin, and hemodynamic profile in overweight and obese adolescent girls and boys (aged 12-16 years). Data were taken from the Multidisciplinary Obesity Treatment Program. Only post-intervention measurements are presented herein. Body composition, cardiorespiratory fitness, blood pressure, and metabolic profile (insulin and glucose profile) of adolescents were assessed. Cardiac parasympathetic activity was determined by resting heart rate variability, which was analyzed using a heart rate monitor. Greater parasympathetic cardiac activity was associated with higher levels of cardiorespiratory fitness in both girls and boys (0.375 ≤ r ≤ 0.900), while the sympathetic-vagal balance was negatively related to maximal oxygen uptake (VO2max) in girls (r = 0.478). An association between lower parasympathetic activity and insulin resistance was noted in girls (mean of R-R intervals [RRmean] and homeostasis model assessment insulin-resistance index [HOMA-IR]: r = -0.678), while greater systolic blood pressure (SBP) and lower parasympathetic activity were associated in both sexes (RRmean and SBP: r = -0.526; high frequency [HF (nu)] and SBP: r = -0.754). In conclusion, autonomic nervous system activity was associated with cardiorespiratory fitness, insulin resistance, and SBP in overweight and obese adolescents. The identification of these potential relationships assists with the establishment of future long-term exercise interventions that evaluate the improvements in parasympathetic nervous system activity, in addition to metabolic profile and cardiorespiratory fitness in overweight and obese adolescents.

Nonalcoholic fatty liver disease and bariatric surgery in adolescents

Obesity is a multi-organ system disease with underlying insulin resistance and systemic chronic inflammation. Nonalcoholic fatty liver disease (NAFLD) is a hepatic manifestation of the underlying metabolic dysfunction. This review provides a highlight of the current understanding of NAFLD pathogenesis and disease characteristics, with updates on the challenges of NAFLD management in obese and severely obese (SO) patients and recommendations for the pediatric surgeons' role in the care of SO adolescents.

Association between insulin-like growth factor-1, measures of overnutrition and undernutrition and insulin resistance in black adolescents living in the North-West Province, South Africa

OBJECTIVE

To determine if insulin-like growth factor-1 (IGF-1) is a significant predictor of body fat percentage (%BF), lean body mass, and insulin resistance (IR) in black adolescents presenting with overnutrition and undernutrition.

METHODS

A cross-sectional study was undertaken in 181 adolescents (111 girls, 70 boys, 13-20 years old) from a low socio-economic population in the North-West Province, South Africa. Anthropometric measurements were performed, and %BF and lean mass were assessed by air displacement plethysmography. Serum glucose, leptin, insulin, IGF-1 and IGF-binding protein-3 (IGFBP-3) were measured and homeostasis model assessment of IR (HOMA-IR) was calculated. Predictors of body composition and HOMA-IR were determined in multivariate linear regressions.

RESULTS

Of the boys, 31% had a %BF >20%, whereas 42% of girls had a %BF >30%. Furthermore, 17.1% male and 18.9% female adolescents were stunted, indicating overnutrition and undernutrition in the same group. IGF-1 showed a negative association with %BF in both sexes, and a positive correlation with height-for-age z-score (HAZ) and lean mass, respectively, in the boys. IGF-1 correlated positively and physical activity correlated negatively with fasting insulin and HOMA-IR in the girls. In both sexes, leptin had the strongest association with %BF in multiple regressions. Leptin and Tanner stage were significant predictors of HOMA-IR in girls, but not in boys.

CONCLUSIONS

IGF-1 was positively associated with lean mass and HAZ in boys, indicating a beneficial relationship with linear growth, but with IR in the girls, indicating possible adverse metabolic effects in the presence of high %BF and physical inactivity.

Effect of modest changes in BMI on cardiovascular disease risk markers in severely obese, minority adolescents

SUMMARY

BACKGROUND

African American and Hispanic adolescents have disproportionately higher rates of obesity compared to white adolescents. In adults, modest weight loss of five percent improves CVD risk marker levels. Less is known about the effects of modest changes in BMI on CVD risk markers in adolescents, particularly newer markers such as C reactive protein (CRP), lipoprotein (a) and homocysteine.

OBJECTIVE

To examine the effect of modest BMI change on CVD risk marker levels in a group of severely obese, African American and Hispanic adolescents.

STUDY DESIGN

A six-month longitudinal analysis.

SUBJECTS

Eighty-three African American and Hispanic adolescents were recruited (mean age ± sd: 15.1 ± 2.0 years); 50 (60%) were reevaluated at 6 ± 2 months.

RESULTS

At baseline, mean BMI was 42.3 ± 7.8 kg/m(2). BMI directly correlated with CRP (p = < 0.001); homocysteine (p = 0.02); insulin (p = 0.05); and systolic and diastolic blood pressures (both p = <0.001). BMI remained significantly associated with CRP and insulin after adjusting for age, sex and ethnicity (p = 0.001). At six-month follow up, there was a significant p for trend between the three groups of BMI change (those with a ≥5% BMI decrease, those who maintained BMI within 5% and those with ≥5% BMI increase) and CRP (p = 0.05) and insulin (p = 0.04).

CONCLUSIONS

A modest decrease in BMI is associated with improvement in CRP and insulin levels. Obese adolescents should be encouraged to continue with modest weight loss goals as they result in improvement in cardiovascular disease risk markers.

Inverse correlation of serum inflammatory markers with metabolic parameters in healthy, Black and White prepubertal youth

OBJECTIVE

To examine for the first time the associations between pro-inflammatory cytokines and obesity-related metabolic biomarkers in, exclusively prepubertal, otherwise healthy obese and non-obese Black and White children, 7-9 years of age.

DESIGN AND METHODS

Body mass index (BMI), homeostasis model assessment-estimated insulin resistance, visceral adipose tissue and subcutaneous adipose tissue (SAT (magnetic resonance imaging)); total body fat (dual-energy X-ray absorptiometry), ectopic, intrahepatic lipid (IHL) and intramyocellular lipid (IMCL) fat (proton magnetic resonance spectroscopy) and serum levels of interleukin (IL)-1, IL-6, IL-8, tumor necrosis factor alpha (TNF-α) and monocyte chemoattractant protein-1 were measured in 40 obese and non-obese children. Relationships between inflammatory cytokines and obesity were assessed by analysis of variance and Spearman's rank correlation.

RESULTS

Significant inverse correlations were found between BMI z-score, SAT, total BF, and IHL and levels of TNF-α (Spearman's ρ=-0.36, -0.39, -0.43 and -0.39, respectively; P<0.05). Levels of IL-8 were significantly and inversely correlated with IMCL (-0.39; P=0.03) and remained significant after adjusting for race. IMCL was inversely associated with TNF-α only after adjusting for race (-0.37; P=0.04).

CONCLUSIONS

Relationships between pro-inflammatory and metabolic markers commonly observed in adults are reversed in healthy, Black and White children before puberty. Prospective studies are warranted to determine how these inverse relationships modify chronic disease risk later in life.

Maturity-associated variation in total and depot-specific body fat in children and adolescents

OBJECTIVES

This study considered the association between sexual maturation and adiposity in children and adolescents, and examined the contribution of sexual maturation to ethnic differences in total and depot-specific body fat.

METHODS

The sample included 382 White and African American 5-18-year-olds. Body mass index (BMI), waist circumference (WC) and sexual maturity status (breast/genital and pubic hair stage) were assessed in a clinical setting. Total body fat (TBF) was measured by dual-energy X-ray absorptiometry and abdominal subcutaneous (SAT) and visceral adipose tissue (VAT) were measured by magnetic resonance imaging. Analysis of covariance adjusted for age was used to examine the association between sexual maturity status and adiposity, and linear regression adjusted for age was used to examine the influence of sexual maturation on ethnic differences in adiposity. Analysis of VAT also controlled for TBF. Significance was accepted at P < 0.05.

RESULTS

Breast/genital stage was significantly associated with BMI, WC, TBF, and SAT in girls of both ethnic groups and in White boys. Breast stage was associated with VAT. Stage of pubic hair was significantly associated with TBF and VAT in White girls only. In girls, sexual maturation attenuated the ethnic effects on BMI and WC, but the ethnic effect in VAT persisted. In boys, sexual maturation did not attenuate ethnic differences on VAT and did not predict WC or SAT. Sexual maturity status independently explained variance in adiposity in girls only.

CONCLUSIONS

Sexual maturity status is an important determinant of pediatric adiposity and attenuates ethnic differences in girls' adiposity.

Nonalcoholic fatty liver disease in severely obese adolescent and adult patients

OBJECTIVES

Nonalcoholic fatty liver disease (NAFLD) is increasingly an indication for liver transplantation in adults. While severe obesity (SO, BMI ≥40 kg m(-2) ) in adults is long standing, it is recent in duration in adolescents. With adolescent obesity on the rise, NAFLD is becoming the most frequent liver disease in adolescents. The hypothesis that SO adolescents and adults have different severity of NAFLD because of longer duration of obesity in SO adults was tested.

DESIGN AND METHODS

Preoperative clinical data, NAFLD activity and NASH (Nonalcoholic steatohepatitis) scores from intraoperative liver biopsies were extracted from a prospective database of consecutively operated SO adolescents and adults (n = 24 each). Fasting preoperative serum inflammatory mediators were evaluated by ELISA.

RESULTS

Other than age, baseline BMI, ethnicity and gender distribution, the incidence and extent of dyslipidemia, hypertension, and metabolic syndrome were comparable between groups. Histologic scores for steatosis and inflammation were similar. Adolescents have significantly higher NASH incidence, hepatocyte injury scores and fibrosis. This was associated with higher serum C-reactive protein and sCD14 levels.

CONCLUSION

For comparable BMI and metabolic profile, SO adolescents have more advanced liver damage, more severe systemic inflammation, suggesting differences in NAFLD etiologies and more aggressive disease progression in the young obese population.

Etiology of insulin resistance in youth with type 2 diabetes

Type 2 diabetes (T2DM), historically an adult disease, is now increasingly prevalent in obese youth. Poor diet and increased sedentary behavior contribute to the increasing rates of obesity in youth, yet not all obese children develop T2DM. In general, T2DM is characterized by both insulin resistance (IR) and pancreatic beta-cell insufficiency. In children, IR is related to elevated body mass index (BMI) and pubertal hormones, along with abnormal fat partitioning, elevated free fatty acids, inflammation, and/or mitochondrial dysfunction. Hyperglycemia and T2DM develop when the pancreas cannot match the increased insulin demands resulting from IR. Unique to youth, IR varies with stage of pubertal development, and some children may have resolution of hyperglycemia post-puberty once the IR of puberty resolves. Further understanding of IR, the progression to T2DM in youth, and later outcomes as adults will help direct future therapies and interventions for youth at risk.

GCKR variants increase triglycerides while protecting from insulin resistance in Chinese children

BACKGROUND

Variants in gene encoding glucokinase regulator protein (GCKR) were found to have converse effects on triglycerides and glucose metabolic traits. We aimed to investigate the influence of GCKR variants for triglycerides and glucose metabolic traits in Chinese children and adults.

METHODS AND RESULTS

We genotyped two GCKR variants rs1260326 and rs1260333 in children and adults, and analyzed the association between two variants and triglycerides, glucose, insulin and HOMA-IR using linear regression model, and estimated the effect on insulin resistance using logistic regression model. Rs1260326 and rs1260333 associated with increased triglycerides in children and adults (p<0.05). In children, both variants significantly reduced insulin (p<0.05. for rs1260326, β = -0.07; for rs1260333, β = -0.07) and HOMA-IR (p<0.05. for rs1260326, β = -0.03; for rs1260333, β = -0.03). There were significant associations between two variants and insulin resistance for children. Under co-dominant model, for CT vs. CC, OR is 0.83 (95%CI 0.69-1.00) for rs1260326, and 0.83 (95%CI 0.68-1.00) for rs1260333; for TT vs. CC, OR is 0.72 (95%CI 0.58-0.88) for rs1260326, and 0.72 (95%CI 0.58-0.89) for rs1260333. Under allele model, for allele T vs. C, the ORs are 0.85 (95%CI 0.76-0.94) and 0.85 (95%CI 0.76-0.94) for rs1260326 and rs1260333, respectively).

CONCLUSIONS

Our study confirmed the associations between GCKR variants and triglycerides in Chinese children and adults. Triglycerides-increasing alleles of GCKR variants reduce insulin and HOMA-IR index, and protect from insulin resistance in children. Our results suggested GCKR has an effect on development of insulin resistance in Chinese children.

Metabolic syndrome and its components among obese (BMI >=95th) Mexican adolescents

The aim of this study was to estimate the prevalence of metabolic syndrome (MS) and its components in obese Mexican adolescents and to compare the clinical, anthropometric, and biochemical characteristics between patients with and without MS by sex. We conducted a cross-sectional study with a sample of 110 obese adolescents (boys and girls) from 8 to 16 years old (BMI ≥95th percentile), who were recruited in the pediatric obesity clinic of a third-level care hospital. A frequency analysis was used to estimate the prevalence of MS and its components, and the assessments were compared between the sexes and between the groups with and without MS using the Kruskal-Wallis test. The prevalence of MS was 62%. IN ORDER OF PREVALENCE, THE FOLLOWING COMPONENTS OF MS WERE OBSERVED IN THE SAMPLE: abdominal obesity (88%), high triglycerides (TG) (85%), low HDL-C (60%), hypertension (35%), and hyperglycemia (5%). In the groups with MS, hypertension (P<0.001), waist circumference (P=0.003), and TG (P=0.012) were significantly higher, and HDL-C (P<0.001) was significantly lower. In conclusion the prevalence of MS and its components is high among obese Mexican-Hispanic children. These findings show the importance of preventing and treating obesity in the early stages of life in order to decrease the incidence rates of cardiovascular disease and type 2 diabetes mellitus.

Tanner Staging of Secondary Sexual Characteristics and Body Composition, Blood Pressure, and Insulin in Black Girls

OBJECTIVE

To assess Tanner staging (breast and pubic hair development) and its relationship to measures of body composition, blood pressure, and fasting insulin and glucose in young black girls.

RESEARCH METHODS AND PROCEDURES

Subjects were 138 black girls, 8 to 12 years of age, recruited from elementary schools in low socioeconomic status neighborhoods. Exclusion criteria included the presence of any acute/chronic medical conditions. Pubertal stages were assessed by one of two pediatricians and analyzed individually, as well as with a composite index (prepubertal, pubertal/premenarcheal, or pubertal/menarcheal). Glucose and insulin were measured after a 12-hour fast. Measures of body composition included height, weight, BMI, waist and hip circumferences, fat mass, fat-free soft tissue, bone mineral density (DXA), and visceral adipose tissue (magnetic resonance imaging). Resting systolic and diastolic blood pressure were measured by Dinamap.

RESULTS

With age in the model, breast development explained significant proportions of the variance in height, weight, fat-free soft tissue, bone mineral density, and insulin. Adding pubic hair development or menarche to those models did not significantly increase the proportion of variance that was explained by breast development. Furthermore, using a composite index of pubertal staging explained a smaller proportion of the variance compared with breast development alone.

DISCUSSION

Combined with age, breast development was a better predictor of body composition and fasting insulin than was pubic hair development or a composite index of pubertal staging.

Adiposity in children and adolescents: correlates and clinical consequences of fat stored in specific body depots

The 2011 Pennington Biomedical Research Center's Scientific Symposium focused on adiposity in children and adolescents. The symposium was attended by 15 speakers and other invited experts. The specific objectives of the symposium were to (i) integrate the latest published and unpublished findings on the laboratory and clinical assessment of depot-specific adiposity in children and adolescents, (ii) understand the variation in depot-specific adiposity and related health outcomes associated with age, sex, maturation, ethnicity and other factors and (iii) identify opportunities for incorporating new markers of abdominal obesity into clinical practice guidelines for obesity in children and adolescents. This symposium provided an overview of important new advances in the field and identified directions for future research. The long-term goal of the symposium is to aid in the early identification of children and adolescents who are at increased health risk because of obesity and obesity-related conditions.

Association of changes in body fatness and fatty acid composition of plasma phospholipids during early puberty in Japanese children

AIMS

Plasma fatty acid composition can change with age, reflecting diet and levels of desaturating enzymes such as stearoyl-CoA desaturase (SCD), delta-6 desaturase (D6D) and delta-5 desaturase (D5D), which contribute to the development of insulin resistance. This study analyzed longitudinal changes in fatty acid composition in Japanese children during early puberty and the association between changes in desaturase indices and changes in body fatness and insulin resistance.

METHODS

The study included 77 children (38 boys and 39 girls) aged 9.6±0.5 years. Relative weight (RW) and waist-to-height ratio (WHtR) were determined. The fatty acid composition of plasma phospholipids was analyzed by gas chromatography, and the desaturase indices were calculated: SCD (16:1n-7/16:0: SCD16 and 18:1n-9/18:0: SCD18), D6D (20:3n-6/18:2n-6) and D5D (20:4n-6/20:3n-6) in 2006 and 2009.

RESULTS

Obese children showed higher dihomo-gamma linolenic acid (DGLA; 20:3n-6), a higher D6D index and lower D5D index than non-obese children. Longitudinal changes in fatty acid com-position were generally similar in both sexes. Increased D6D index and DGLA and decreased D5D index were significantly associated with increased WHtR in boys and girls. In addition, increased D6D index was associated with an increased homeostasis model of assessment ratio (HOMA-R) only in girls.

CONCLUSION

The change in abdominal adiposity is a determinant of longitudinal changes in D6D and D5D indices and DGLA during early puberty.

Age before stage: insulin resistance rises before the onset of puberty: a 9-year longitudinal study (EarlyBird 26)

OBJECTIVE

Insulin resistance (IR) is associated with diabetes. IR is higher during puberty in both sexes, with some studies showing the increase to be independent of changes in adiposity. Few longitudinal studies have reported on children, and it remains unclear when the rise in IR that is often attributed to puberty really begins. We sought to establish from longitudinal data its relationship to pubertal onset, and interactions with age, sex, adiposity, and IGF-1.

RESEARCH DESIGN AND METHODS

The EarlyBird Diabetes study is a longitudinal prospective cohort study of healthy children aged 5-14 years. Homeostasis model assessment (HOMA-IR), skinfolds (SSF), adiposity (percent fat, measured by dual-energy X-ray absorptiometry), serum leptin, and IGF-1 were measured annually in 235 children (134 boys). Pubertal onset was adduced from Tanner stage (TS) and from the age at which luteinizing hormone (LH) first became serially detectable (≥0.2 international units/L).

RESULTS

IR rose progressively from age 7 years, 3-4 years before TS2 was reached or LH became detectable. Rising adiposity and IGF-1 together explained 34% of the variance in IR in boys and 35% in girls (both P < 0.001) over the 3 years preceding pubertal onset. The contribution of IGF-1 to IR was greater in boys, despite their comparatively lower IGF-1 levels.

CONCLUSIONS

IR starts to rise in mid-childhood, some years before puberty. Its emergence relates more to the age of the child than to pubertal onset. More than 60% of the variation in IR prior to puberty was unexplained. The demography of childhood diabetes is changing, and prepubertal IR may be important.

Association of acanthosis nigricans and skin tags with insulin resistance

Insulin resistance is a metabolic disorder in which target cells fail to respond to normal levels of circulating insulin. Insulin resistance has been associated with presence of acanthosis nigricans and acrochordons. It is known that early diagnosis and early initial treatment are of paramount importance to prevent a series of future complications. These dermatoses may represent an easily identifiable sign of insulin resistance and non-insulin-dependent diabetes.

Change of Body Composition and Adipokines and Their Relationship with Insulin Resistance across Pubertal Development in Obese and Nonobese Chinese Children: The BCAMS Study

A transient increase in insulin resistance (IR) is a component of puberty. We investigated the impact of body composition and adipokines on IR during puberty in Chinese children. This study included 3223 schoolchildren aged 6-18 years. IR was calculated using homeostasis model assessment (HOMA-IR). We revealed that body mass index (BMI) and waist circumference increased gradually during puberty in both genders, while fat-mass percentage (FAT%) increased steadily only in girls. Change of leptin showed striking sexual dimorphisms: in girls leptin increased steadily during puberty, whereas in boys, after a transient rise at the beginning of puberty, leptin declined by Tanner staging even in those overweight or obese. Inversely, adiponectin level decreased significantly during puberty. In both genders, HOMA-IR started to increase at the beginning of puberty, peaked in the middle, and revised at late puberty in overweight/obesity boys while it stayed high till the end of puberty in girls and normal weight boys. Multivariate regression analysis revealed that leptin presented a stronger indicator of HOMA-IR than anthropometric measures during puberty. Our results demonstrated that gender-specific FAT% and leptin changed with pubertal development. Leptin emerged as a stronger predictor of IR than traditional anthropometric indices, suggesting a prominent role in the development of pubertal IR.

Childhood obesity is associated with changes in the serum metabolite profile

OBJECTIVE

The human serum metabolite profile is reflective of metabolic processes, including pathophysiological changes characteristic of diseases. Therefore, investigation of serum metabolite concentrations in obese children might give new insights into biological mechanisms associated with childhood obesity.

METHODS

Serum samples of 80 obese and 40 normal-weight children between 6 and 15 years of age were analyzed using a mass spectrometry-based metabolomics approach targeting 163 metabolites. Metabolite concentrations and metabolite ratios were compared between obese and normal-weight children as well as between children of different pubertal stages.

RESULTS

Metabolite concentration profiles of obese children could be distinguished from those of normal-weight children. After correction for multiple testing, we observed 14 metabolites (glutamine, methionine, proline, nine phospholipids, and two acylcarnitines, p < 3.8 × 10⁻⁴) and 69 metabolite ratios (p < 6.0 × 10⁻⁶) to be significantly altered in obese children. The identified metabolite markers are indicative of oxidative stress and of changes in sphingomyelin metabolism, in β-oxidation, and in pathways associated with energy expenditure. In contrast, pubertal stage was not associated with metabolite concentration differences.

CONCLUSION

Our study shows that childhood obesity influences the composition of the serum metabolome. If replicated in larger studies, the altered metabolites might be considered as potential biomarkers in the generation of new hypotheses on the biological mechanisms behind obesity.

Effectiveness and outcomes of brace treatment: a systematic review

Bracing has been widely used for the treatment of adolescent idiopathic scoliosis (AIS). However, effectiveness of brace treatment remains controversial. A systematic review was conducted to investigate evidence that brace treatment is effective in the treatment of AIS. A total of 20 studies, including randomized controlled trials, nonrandomized clinical controlled trials, or case-control studies, were included. Studies comparing the results of brace treatment with no-treatment, other conservative treatments, or surgical treatment were included. Outcomes of the studies included radiological curve progression, incidence of surgery, pulmonary function, quality of life (QOL), and psychological state. The results from the systematic review are difficult to interpret. There are quite a number of varying parameters between studies that make it very difficult to reach any firm conclusions. In addition, the quality of evidence is limited because most of the studies included in this review were of low methodological quality. However, the available data suggest that, compared to observation, bracing is more potent in preventing the progression of scoliosis and may not have a negative impact on patients' QOL. Therefore, bracing can be recommended for the treatment of AIS, at least for female patients with a Cobb angle of 25-35°. Compared to other conservative treatments, bracing seems to be more effective than electrical stimulation, although an advantage of bracing over side-shift exercise or casting has not been established. Comparison between bracing and surgery is difficult because in most studies, the curve magnitude at baseline was considerably larger in the surgery group. We recommend that future studies have clearer and more consistent guidelines.

Interrelationships among changes in leptin, insulin, cortisol and growth hormone and weight status in youth

OBJECTIVE

While acute alterations in leptin, insulin, cortisol and growth hormone (GH) levels have been reported in children following weight change interventions, little is known about natural hormonal changes as children grow and how these changes are affected by unprovoked weight status changes. The purpose of this investigation was to compare changes in leptin, insulin, cortisol and GH levels in youth who maintained their weight status vs. those who moved from normal weight to overweight or vice versa.

METHODS

Data were collected from 120 youth at baseline (9.8±1.0 years) and two years later. Participants were selected from a larger cohort to represent all scenarios of weight status: normal weight [>5(th) and <85(th) body mass index (BMI) percentile] at both time points (NN), overweight (≥85(th) BMI percentile) at both time points (OO), normal weight status who changed to overweight (NO) and overweight status which changed to normal weight (ON). Hormonal concentrations were measured from fasting venous blood.

RESULTS

In youth who changed their weight status, there were significant associations (p<0.05) between changes in BMI percentile and changes in leptin, insulin and cortisol (partial R(2)=0.35, 0.13 and 0.11, respectively), after accounting for race, sex and changes in pubertal status and aerobic power. Our key findings were that youth who became overweight (NO) showed greater changes for leptin (+205% vs. -21%) and cortisol (-33% vs. +13%), p<0.05 than those who reverted from overweight to normal weight (ON).

CONCLUSION

Natural changes in weight status in youth show a relationship with changes in leptin, insulin and cortisol levels and the hormonal changes appear to be more sensitive to increases, rather than reductions, in weight status.