The effect of puberty on insulin resistance in obese children

Sex differences in cardiometabolic risk factors and in response to lifestyle intervention in prepubertal and pubertal subjects with obesity

Objectives

Childhood obesity is a growing health problem and requires a tailored treatment. This study explored the sex differences in cardiovascular risk factors in children/adolescents with obesity and in response to a weight loss intervention.

Methods

Five hundred and thirty-three children/adolescents with obesity and their parents underwent to a 3-months lifestyle intervention program. Tanner criteria were used to assess the pubertal stage. Before and after 3 months, anthropometric measurements, blood pressure (BP), and biochemical measurements were assessed.

Results

Four hundred and forty five participants completed the treatment (age 12.4 ± 2.7 years, males 45.8%, prepubertal 29.2%, BMI z score 2.3 ± 0.2). In comparison to boys, prepubertal girls had higher values of BMI z score (2.4 ± 02 vs. 2.3 ± 0.2, p < 0.05), waist circumference z score (2.2 ± 0.3 vs. 2.0 ± 0.3, p < 0.05), HOMA-IR [2.9 (2.1-4.9) vs. 2.3(1.5-3.6), p < 0.01], prevalence of hypertransaminasemia (41.3% vs. 17.7%, p < 0.05) and lower levels of HDL cholesterol (46.2 ± 9.8 vs. 51.2 ± 10.5 mg/dl, p < 0.05). In the pubertal stage, boys had worse cardiometabolic risk profile than girls, including unfavourable measure of systolic BP (z score: 0.6 ± 1.0 vs. 0.3 ± 1.0, p < 0.01), fasting glucose (87.2 ± 6.1 vs. 84.8 ± 7.7 mg/dl, p < 0.01), ALT (26.9 ± 21.5 vs. 20.2 ± 10.6 U/L, p < 0.001) and uric acid (6.1 ± 1.9 vs. 5.0 ± 1.0 mg/dl, p < 0.001). After the lifestyle intervention, changes in BMI z score (p < 0.05) were higher in pubertal boys than pubertal girls. The systolic blood pressure decrease was greater in pubertal boys than in their female counterpart (Δ systolic BP: -7.2 mmHg in boys vs. -3.6 mmHg in girls, p < 0.05; Δ systolic BP z score: -0.6 in boys vs. -0.3 in girls, p < 0.05). LDL cholesterol showed an improvement only in boys, and ALT in the whole group.

Conclusion

Our study showed that a short-term lifestyle intervention is more effective in reducing BMI z score and cardiovascular risk factors in pubertal boys than in their female counterparts. Further investigation is needed to deepen this gender difference, especially to develop a tailor-made intervention.

Impact of puberty, sex determinants and chronic inflammation on cardiovascular risk in young people

Worrying trends of increased cardiovascular disease (CVD) risk in children, adolescents and young people in the Modern Era have channelled research and public health strategies to tackle this growing epidemic. However, there are still controversies related to the dynamic of the impact of sex, age and puberty on this risk and on cardiovascular health outcomes later in life. In this comprehensive review of current literature, we examine the relationship between puberty, sex determinants and various traditional CVD-risk factors, as well as subclinical atherosclerosis in young people in general population. In addition, we evaluate the role of chronic inflammation, sex hormone therapy and health-risk behaviours on augmenting traditional CVD-risk factors and health outcomes, ultimately aiming to determine whether tailored management strategies for this age group are justified.

Skeptical Look at the Clinical Implication of Metabolic Syndrome in Childhood Obesity

Metabolic syndrome (MetS) is defined by a cluster of several cardio-metabolic risk factors, specifically visceral obesity, hypertension, dyslipidemia, and impaired glucose metabolism, which together increase risks of developing future cardiovascular disease (CVD) and type 2 diabetes mellitus (T2D). This article is a narrative review of the literature and a summary of the main observations, conclusions, and perspectives raised in the literature and the study projects of the Working Group of Childhood Obesity (WGChO) of the Italian Society of Paediatric Endocrinology and Diabetology (ISPED) on MetS in childhood obesity. Although there is an agreement on the distinctive features of MetS, no international diagnostic criteria in a pediatric population exist. Moreover, to date, the prevalence of MetS in childhood is not certain and thus the true value of diagnosis of MetS in youth as well as its clinical implications, is unclear. The aim of this narrative review is to summarize the pathogenesis and current role of MetS in children and adolescents with particular reference to applicability in clinical practice in childhood obesity.

Cardiometabolic risk factors among children who are affected by overweight, obesity and severe obesity

Background

The increasing severity of obesity is expected to lead to more serious health effects. However, there is limited information on the prevalence and clinical characteristics of cardiometabolic risk factors in severely children affected by obesity in Malaysia. This baseline study aimed to investigate the prevalence of these factors and their association with obesity status among young children.

Methods

In this study, a cross-sectional design was employed using the baseline data obtained from the My Body Is Fit and Fabulous at school (MyBFF@school) intervention program involving obese school children. Obesity status was defined using the body mass index (BMI) z-score from the World Health Organization (WHO) growth chart. Cardiometabolic risk factors presented in this study included fasting plasma glucose (FPG), triglycerides (TGs), total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), blood pressure, acanthosis nigricans, insulin resistance (IR), and MetS. MetS was defined using the International Diabetes Federation (IDF) 2007 criteria. Descriptive data were presented accordingly. The association between cardiometabolic risk factors, such as obesity status, and acanthosis nigricans with MetS was measured using multivariate logistic regression, which was adjusted for gender, ethnicity, and strata.

Results

Out of 924 children, 38.4% (n = 355) were overweight, 43.6% (n = 403) were obese, and 18% (n = 166) were severely obese. The overall mean age was 9.9 ± 0.8 years. The prevalence of hypertension, high FPG, hypertriglyceridemia, low HDL-C, and the presence of acanthosis nigricans among severely children affected by obesity was 1.8%, 5.4%, 10.2%, 42.8%, and 83.7%, respectively. The prevalence of children affected by obesity who were at risk of MetS in <10-year-old and MetS >10-year-old was observed to be similar at 4.8%. Severely children affected by obesity had higher odds of high FPG [odds ratio (OR) = 3.27; 95% confdence interval (CI) 1.12, 9.55], hypertriglyceridemia (OR = 3.50; 95%CI 1.61, 7.64), low HDL-C (OR = 2.65; 95%CI 1.77, 3.98), acanthosis nigricans (OR = 13.49; 95%CI 8.26, 22.04), IR (OR = 14.35; 95%CI 8.84, 23.30), and MetS (OR = 14.03; 95%CI 3.97, 49.54) compared to overweight and children affected by obesity. The BMI z-score, waist circumference (WC), and percentage body fat showed a significant correlation with triglycerides, HDL-C, the TG: HDL-C ratio, and the homeostatic model assessment for IR (HOMA-IR) index.

Conclusions

Severely children affected by obesity exhibit a higher prevalence of and are more likely to develop cardiometabolic risk factors compared to overweight and children affected by obesity. This group of children should be monitored closely and screened periodically for obesity-related health problems to institute early and comprehensive intervention.

β Cell mass expansion during puberty involves serotonin signaling and determines glucose homeostasis in adulthood

Puberty is associated with transient insulin resistance that normally recedes at the end of puberty; however, in overweight children, insulin resistance persists, leading to an increased risk of type 2 diabetes. The mechanisms whereby pancreatic β cells adapt to pubertal insulin resistance, and how they are affected by the metabolic status, have not been investigated. Here, we show that puberty is associated with a transient increase in β cell proliferation in rats and humans of both sexes. In rats, β cell proliferation correlated with a rise in growth hormone (GH) levels. Serum from pubertal rats and humans promoted β cell proliferation, suggesting the implication of a circulating factor. In pubertal rat islets, expression of genes of the GH/serotonin (5-hydroxytryptamine [5-HT]) pathway underwent changes consistent with a proliferative effect. Inhibition of the pro-proliferative 5-HT receptor isoform HTR2B blocked the increase in β cell proliferation in pubertal islets ex vivo and in vivo. Peripubertal metabolic stress blunted β cell proliferation during puberty and led to altered glucose homeostasis later in life. This study identifies a role of GH/GH receptor/5-HT/HTR2B signaling in the control of β cell mass expansion during puberty and identifies a mechanistic link between pubertal obesity and the risk of developing type 2 diabetes.

Association of Puberty Stage and Weight Status with Cardiometabolic Risk in Children and Adolescents Living on the Texas-Mexico Border

Background: This retrospective cohort study aimed to examine the interaction effect between puberty stage and weight status on individual and clustering of cardiometabolic risk factors (CMRFs) among Mexican American children and adolescents. A total of 333 children and adolescents (aged 8-18 years) enrolled in the Cameron County Hispanic Cohort (CCHC) from 2014 to 2020 were included in the study. Methods: CCHC is a longitudinal, randomly recruited cohort based on the United States Census tracts/blocks of Mexican Americans living on the Texas-Mexico border. Individual CMRFs, including high blood pressure, central obesity, hypertriglyceridemia, low high-density lipoprotein cholesterol, and insulin resistance (IR) were assessed. Clustering of CMRFs is defined as the presence of three or more individual CMRFs. Puberty stages were assessed using the Tanner criteria. Multivariable logistic regressions were conducted to assess the association of puberty, weight status, and the interaction of the two main exposures with individual and clustering of CMRFs. Results: We observed that weight status had a dominant effect on all CMRF measures. The effect was especially prominent on central obesity and clustering of CMRFs. There were 95.4% of children with central obesity and 98.4% of those with clustering of CMRF were either overweight or obese. Entering puberty was associated with an increased risk of having IR [Tanner stage 2 vs. 1: odds ratio (OR) = 3.25, 95% confidence interval (95% CI) 1.28-8.27; Tanner stage 3 vs. 1: OR = 3.50, 95% CI 1.45-8.46] and hypertriglyceridemia (Tanner stage 2 vs. 1: OR = 2.67, 95% CI 1.11-6.45). However, the effects were not observed among those reaching the end of puberty (Tanner stage 4 and 5). Conclusions: A significant interaction effect between weight status and puberty was not detected on any individual CMRF and in the clustering of CMRFs. Other factors positively associated with individual CMRFs, especially IR, were being female and having a family history of diabetes.

Association of the triglyceride-glucose index with weight-adjusted appendicular lean mass in Chinese adolescents aged 12-18 years old

There is no study exploring the association between triglyceride-glucose (TyG) index and skeletal muscle mass in Chinese adolescents. Therefore, the objective of this study is to explore the association between TyG index and appendicular lean mass (ALM) in Chinese adolescents. In this study, 1336 adolescents (805 boys, 60.25%) aged 12-18 years in China were randomly selected through a stratified cluster sampling. According to the tertiles of TyG index, we separated all participants into three groups, and LM was measured by Bioelectrical Impedance Analysis. The TyG index was negatively related to ALM/weight in Chinese adolescents whether stratified by gender (boys: β = - 0.293; girls: β = - 0.195; all P < 0.001). After adjusting for age and BMI, a significant correlation between the TyG index and ALM/weight was observed only in boys (β = - 0.169, P = 0.001). The highest TyG index tertile was significantly associated with low ALM/weight after adjusting for all covariates in the full sample (OR = 3.04, 95% CI 1.12-8.26, P = 0.029) and boys (OR = 4.68, 95% CI 1.22-17.95, P = 0.025) only in overweight/obese group. Our findings suggested elevated levels of TyG index may be a risk factor of low ALM/weight in Chinese adolescents, especially in boys.

Prediction of Insulin Resistance Based on Anthropometric and Clinical Variables in Children with Overweight or Obesity at a Tertiary Center in Northeast Mexico

Background: This study provides a clinical model to identify children with insulin resistance (IR) in health care units where laboratory tests are not readily available. Methods: A retrospective study of Mexican children aged 2-16 years at an obesity (OB) clinic. A receiver operating characteristic (ROC) curve was used to assess the accuracy of the proposed model consisting of clinical parameters and to establish the cutoff value for the variables (439 children). A second cohort of children with similar characteristics served as the cohort for the validation of the model (577 children). Results: To determine the best model for predicting IR, we performed a multivariate logistic regression analysis, which showed that waist circumference, acanthosis nigricans, and pubertal status are independent predictors of IR, and when integrated, their predictive power increases. Based on this model, we constructed a simplified equation. The predictive tool was constructed using an ROC curve, with an area under the curve of 0.849. A cutoff value of 7.68 was selected based on the Youden Index, with sensitivity and specificity of 78.3% and 83.3%, respectively. Incorporating metabolic laboratory determinations with a cutoff value of 20.64 improved the sensitivity to 94.9%. Conclusions: We developed a simple and affordable method of identifying IR in children with overweight or OB based on anthropometric variables and routine blood tests for metabolic indicators, such as glucose and triglycerides, which can be implemented in underserved sites.

Ability of TyG Index as a Marker of Insulin Resistance in Argentinean School Children

OBJECTIVE

To determine if the triglycerides and glucose index (TyG) can be used as a marker for insulin resistance (IR) in Argentinean schoolchildren according to age and sex.

METHODS

Anthropometric data, blood glucose levels, lipid profiles, and insulin levels were measured. The TyG index was defined by Ln [fasting triglyceride (mg/dL)* fasting glucose (mg/dL)/2]. A comparison of the ability of TyG to identify children with IR was performed using receiver operating characteristic (ROC) curves and the area under the ROC (AUROC) curve. IR was defined as HOMA-IR > III quartile.

RESULTS

A total of 915 (528, 57.7% males) apparently healthy schoolchildren, aged 9.3 ± 2.2, were evaluated. The AUROC using the HOMA-IR > III quartile as the dichotomous variable showed that TyG was a fair marker to identify IR (0.65, 95% CI, 0.61-0.69; p < 0.01). There was a significantly higher TyG AUROC in males (0.69, 95% CI, 0.63-0.75; p < 001) than in females (0.60, 95% CI, 0.54-0.66; p < 0.01). When children were divided according to age into two groups (5.0-9.9 and 10.0-14.9-year-olds); younger children (0.64, 95% CI, 0.58-0.69; p < 0.011) and older children (0.62, 95% CI, 0.55-0.68; p = 0.01) had a similar and fair AUROC. However, when children were divided by age and sex, females older than ten had a non-significant AUROC (0.53, 95% CI, 0.42-0.63; p = 0.61). The TyG index compared with HOMA-IR had low sensitivity and specificity, ranging from 0.62 to 0.56.

CONCLUSION

The TyG index had a fair AUROC with low sensitivity and specificity, indicating poor discrimination in identifying IR in apparently healthy Argentinean children. The ability to use TyG for screening purposes seems limited in Argentinean schoolchildren.

A population-based study of TyG index distribution and its relationship to cardiometabolic risk factors in children and adolescents

The purpose of this study was to present age- and sex-specific distributions of the triglyceride-glucose (TyG) index and to evaluate their relationship with cardiometabolic risk factors in children and adolescents. A total of 7404 participants aged 10-18 years from the Korean National Health and Nutrition Survey were included as the reference population. The TyG index was calculated as ln(fasting triglyceride [mg/dL] × fasting glucose [mg/dL]/2). The percentile of the TyG index exhibited a steady linear relationship with age for both sexes. TyG index significantly correlated with waist circumference (WC) standard deviation score (SDS; r = 0.110, p < 0.001), systolic blood pressure (SBP; r = 0.104, p < 0.001), diastolic blood pressure (DBP; r = 0.083, p < 0.001), glucose (r = 0.220, p < 0.001), high-density lipoprotein cholesterol (HDL-C; r = - 0.325, p < 0.001), and triglycerides (TG; r = 0.926, p < 0.001). Multiple linear regression analysis revealed that the TyG index was significantly associated with WC SDS (β = 0.116, p < 0.001), SBP (β = 2.009, p < 0.001), DBP (β = 1.464, p < 0.001), glucose (β = 3.376, p < 0.001), HDL-C (β =  - 6.431, p < 0.001), and TG (β = 85.518, p < 0.001). Our results suggest that the TyG index has a steady linear distribution for sex and age in children and adolescents and constitutes an indicator for predicting metabolic disorders that could lead to cardiovascular disease later in life.

Diabetes mellitus als mögliche Spätmanifestation eines hämolytisch-urämischen Syndroms

Ein 13-jähriger Junge erkrankte 10 Jahre nach einem hämolytisch-urämischen Syndrom durch Shigatoxin bildende enterohämorrhagische E. coli (STEC-HUS) an einem insulinpflichtigen Diabetes mellitus.

Die Diagnostik ergab keine Hinweise auf eine Insulinresistenz, sondern auf einen Insulinmangel ohne Nachweis von diabetesspezifischen Autoantikörpern. Ein „maturity-onset diabetes of the young“ (MODY), Typen 1–13, war molekulargenetisch nicht nachweisbar.

In der Literatur findet sich eine Reihe von Berichten über das Auftreten eines Diabetes mellitus viele Jahre nach Manifestation eines STEC-HUS mit insulinpflichtigen Hyperglykämien in der Akutphase. Dieser Artikel beschreibt den Fall eines Patienten mit insulinpflichtigem Diabetes mellitus nach STEC-HUS ohne insulinpflichtige Hyperglykämien in der Akutphase des HUS. Dies unterstreicht die Notwendigkeit einer langfristigen Nachsorge aller Patienten nach HUS.

The effect of eight-week walking program on plasma levels of amino acids in early/mid pubertal obese girls

Background: Altered circulating amino acids levels have been observed in metabolic disorders, like obesity, type-2 diabetes, and other insulin-resistant states. This study aimed to investigate the effect of 8-week walking on plasma amino acids (PAAs) in obese girls. Methods: This clinical trial study (IRCT20180928041160N1) was conducted on 32 early/mid pubertal obese girls which they divided into interval-walking (IWG, n=12), continuous-walking (CWG, n=11) and control (CG, n=9) groups. The walking program (3- sessions/week for 8-weeks) consists of 30-min walking with 70-85%HRmax and 60-75%HRmax, respectively in the IWG (2-min walking and 1-min active rest) and CWG. The concentration of PAAs was measured at baseline and 72-hours after the last session in fasting state, using high-performance liquid chromatography. A repeated measures ANCOVA (group (3) * time (2)) with post hoc Bonferroni was used to analyze the data. Results: More the PAAs were not affected by interval or continuous walking training. A significant increase in lysine (p=0.003, 95%CI 24.08, 108.97) was observed only in the CG, and there was a significant difference between the CG and CWG (p=0.032). Global arginine bioavailability (GABA) significantly decreased in the CG (P<0.001, 95%CI -0.65, -0.21) and the IWG (p=0.004, 95%CI -0.60, -0.21). A significant increase in weight (p=0.043, 95%CI 0.27, 1.46), insulin (p=0.046, 95%CI -0.91, 9.01), and HOMA-IR (p=0.007, 95%CI 0.26, 2.63) were found only in the CG, and both insulin and HOMA-IR tended to decline in the CWG. Conclusion: Except for lysine and GABA, all groups roughly showed similar changes in more amino acids. Continuous-walking could improve the plasma level of lysine and GABA, which along with an improvement of fasting insulin levels and HOMA-IR.

Gender-based differences in the clustering of metabolic syndrome factors in children and adolescents

Background We depicted gender-differences in metabolic syndrome (MS) clustering before and after puberty in pediatrics, in order to develop gender specific preventive strategies for childhood obesity. Methods We considered 1079 children and adolescents (529 females and 550 males; mean age 11.5 ± 2.8 year). According to body mass index (BMI) percentiles the subjects were classified as normal weight BMI <75th, overweight BMI 75-95th and with obesity BMI >95th. MS was diagnosed when three of the following criteria for age and sex percentiles were met: BMI >95th, triglycerides (TGs) level >95th, high-density lipoprotein-cholesterol (HDL-c) level <5th, blood pressure (blood pressure) >95th percentile, fasting blood glucose (FBG) >100 mg/dL and/or homeostatic model assessment- insulin resistance (HOMA-IR) >97.5th percentile. Results The prevalence of dismetabolic factors was similar in both genders, except for pathological BP, which was higher in males (p = 0.02). MS was detected only in patients with obesity, with a higher prevalence in pubertal than late/post-pubertal subjects (p < 0.001), without any significant difference between gender. In pre-puberty, the most common MS combination was obesity (HBMI) + hypertension (HBP) + hyperglycemia/insulin resistance (HGLY/IR) followed by HBMI + low HDL-levels (LHDL) + HGLY/IR versus HBMI + HBP + HGLY/IR followed by HBMI + HBP + LHDL, respectively, in females and males. In the early and late/post-pubertal periods, the most prevalent combination remained similar to pre-puberty, additionally in both sexes other combinations, such as HBMI + HTG + HBP + HGLY/IR, HBMI +  HBP + LHDL + HGLY/IR, HBMI + HTG + LHDL + HGLY/IR and HBMI + HTG + LHDL + HBP + HGLY/IR were also detected, differently distributed in males and females. Conclusions We confirm that MS is an important consequence related to obesity, particularly in the post-puberty stage. Some gender-based differences should be considered early in order to identify specific preventive and treatment strategies.

Obesity and insulin sensitivity effects on cardiovascular risk factors: Comparisons of obese dysglycemic youth and adults

BACKGROUND

Obesity and pubertal insulin resistance worsen cardiovascular (CV) risk factors in youth. It is unclear how the relationships of obesity and insulin resistance with CV risk compare to adults.

SUBJECTS AND METHODS

We evaluated 66 pubertal youth (mean ± SD: age 14.2 ± 2.0 years, body mass index [BMI] 36.6 ± 6.0 kg/m² , hemoglobin A1c [HbA1c] 38.5 ± 6.1 mmol/mol) and 355 adults with comparable BMI (age 52.7 ± 9.4 years, BMI 35.1 ± 5.1 kg/m² , HbA1c 39.8 ± 4.2 mmol/mol) participating in a multicenter study. Insulin sensitivity was quantified using hyperglycemic clamps. Assessment of CV risk factors was standardized across sites. Regression analyses compared the impact of insulin sensitivity and CV risk factors between youth and adults.

RESULTS

Obese pubertal youth were more insulin resistant than comparably obese adults (P < .001), but with similar slopes for the inverse relationship between insulin sensitivity and obesity. The impact of obesity on CV risk factors was explained by insulin sensitivity (P = NS after adjustment for sensitivity). The two age groups did not differ in relationships between insulin sensitivity and diastolic blood pressure, total cholesterol, and low-density lipoprotein (LDL) cholesterol, after adjusting for obesity. However, while systolic blood pressure (SBP) and high-density lipoprotein (HDL) cholesterol exhibited the expected direct and inverse relationships, respectively with insulin sensitivity in adults, these slopes were flat in youth across the range of insulin sensitivity (P ≤ .05 for group differences).

CONCLUSIONS

Effects of obesity on CV risk factors were attributable to insulin sensitivity in both groups. The relationships between insulin sensitivity and CV risk factors were similar in obese youth and adult groups except for SBP and HDL cholesterol.

CLINICAL TRIAL REGISTRATION

The RISE consortium studies are registered through Clinicaltrials.gov as NCT01779362 (Adult Medication Study); NCT01763346 (Adult Surgery Study); and NCT01779375 (Pediatric Medication Study). Clinical trial registration numbers: NCT01779362, NCT01779375 and NCT01763346 at clinicaltrials.gov.

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.

The effect of overweight on the luteinizing hormone level after gonadorelin stimulation test in girls with idiopathic central precocious puberty

PURPOSE

We investigated the effect of overweight on luteinizing hormone (LH) levels after a gonadorelin stimulation test in Korean girls with idiopathic central precocious puberty (CPP).

METHODS

Medical records of 234 girls diagnosed with idiopathic CPP were reviewed retrospectively. CPP was diagnosed when the peak LH levels after gonadorelin stimulation was &gt;5.0 U/L. The enrolled girls had a peak LH level &gt;5.0 U/L after a gonadorelin stimulation test. Selected girls were classified as normoweight (body mass index [BMI] below the 85th percentile with respect to age) and overweight (BMI greater than the 85th percentile with respect to age).

RESULTS

The peak LH (8.95±2.85 U/L vs. 11.97±8.42 U/L, P&lt;0.01) and peak follicle-stimulating hormone (9.60±2.91 U/L vs. 11.17±7.77 U/L, P=0.04) after gonadorelin stimulation were lower in overweight girls with idiopathic CPP than in normoweight girls with idiopathic CPP. Being overweight was negatively associated with peak LH levels after gonadorelin stimulation test (odds ratio, 0.89; 95 % confidence interval, 0.81-0.98, P=0.02).

CONCLUSION

In girls with idiopathic CPP, being overweight led to a lower LH peak after gonadorelin stimulation. Further research is needed to better understand the role of overweight on gonadotropin secretion in precocious puberty.

The Influence of Obesity on Puberty and Insulin Resistance in Mexican Children

Obesity is considered the main risk factor associated with the development of insulin resistance (IR). The aim of this study was to evaluate the influence of obesity on puberty onset and IR in Mexican children. A total of 378 children (189 boys and 189 girls) aged 8-14 years participated in the study. IR was estimated using the homeostasis model assessment for IR (HOMA-IR). The mean fasting glucose (FG) and basal insulin levels were 82 mg/dl and 11.0 μIU/ml in boys and 77.3 mg/dl and 12.3 μIU/ml in girls (P < 0.05). Subjects with obesity at Tanner stages II-V showed increased FG levels (P < 0.05). In boys with obesity, there was a decrease in HOMA-IR in Tanner stage IV and differences in age between boys with normal weight and those with obesity in Tanner V, being older the boys with obesity. Obesity in children and adolescents was associated with higher HOMA-IR values. In boys with obesity, IR increased at the end of pubertal maturation, with a delay in puberty. These findings should be considered on the establishment of IR cutoff values for pubertal population in Mexico and in the establishment of strategies to prevent the health problems related to obesity.

Inappropriate Use of Homeostasis Model Assessment Cutoff Values for Diagnosing Insulin Resistance in Pediatric Studies

Background

Assessing pediatric patients for insulin resistance is one way to identify those who are at a high risk of developing type 2 diabetes mellitus. The homoeostasis model assessment (HOMA) is a measure of insulin resistance based on fasting blood glucose and insulin levels. Although this measure is widely used in research, cutoff values for pediatric populations have not been established.

Objective

To assess the validity of HOMA cutoff values used in pediatric studies published in peer-reviewed journals.

Methods

Studies published from January 2010 to December 2015 were identified through MEDLINE. Initial screening of abstracts was done to select studies that were conducted in pediatric populations and used HOMA to assess insulin resistance. Subsequent full-text review narrowed the list to only those studies that used a specific HOMA score to diagnose insulin resistance. Each study was classified as using a predetermined fixed HOMA cutoff value or a cutoff that was a percentile specific to that population. For studies that used a predetermined cutoff value, the references cited to provide evidence in support of that cutoff were evaluated.

Results

In the 298 articles analyzed, 51 different HOMA cutoff values were used to classify patients as having insulin resistance. Two hundred fifty-five studies (85.6%) used a predetermined fixed cutoff value, but only 72 (28.2%) of those studies provided a reference that supported its use. One hundred ten studies (43%) that used a fixed cutoff either cited a study that did not mention HOMA or provided no reference at all. Tracing of citation history indicated that the most commonly used cutoff values were ultimately based on studies that did not validate their use for defining insulin resistance.

Conclusion

Little evidence exists to support HOMA cutoff values commonly used to define insulin resistance in pediatric studies. These findings highlight the importance of validating study design elements when training medical students and novice investigators. Using available data to generate population ranges for HOMA would improve its clinical utility.

Metabolic Profiles in Obese Children and Adolescents with Insulin Resistance

BACKGROUND:

In the past several decades, the increasing frequency of overweight and obese children and adolescents in the world has become a public health problem. It has contributed significantly to the already high tide of diabetes, cardiovascular and cerebrovascular diseases.

AIM:

To investigate the frequency of insulin resistance and to evaluate the metabolic profile of insulin resistant and non-insulin resistant obese children and adolescents.

SUBJECTS AND METHODS:

The study included 96 (45 boys, 51 girls) obese children and adolescents aged 4-17 years old (10.50 ± 2.87 years). Only participants with Body Mass Index ≥ 95 percentile were included. We analysed sera for fasting insulin levels (FI), fasting serum triglycerides (TG), total serum cholesterol (TC), fasting plasma glucose (FPG) and plasma glucose 2 hours after the performance of the oral glucose tolerance test (2-h G). Homeostatic model assessment for insulin resistance (HOMA-IR) index was calculated as fasting insulin concentration (microunits per millilitre) x fasting glucose concentration (millimolar)/22.5. The value of HOMA-IR above 3.16 was used as a cut-off value for both genders.

RESULTS:

Insulin resistance was determined in 58.33% of study participants. Insulin resistant participants had significantly higher level of 2-h G (p = 0.02), FI level (p = 0.000) as well as TG levels (p = 0.01), compared to non-insulin resistant group. Strikingly, 70.73% of the pubertal adolescents were insulin resistant in comparison to 49.09% of the preadolescents (p = 0.03). Significantly higher percentage of insulin-resistant participants were girls (p = 0.009). Moreover, a higher percentage of the girls (70.59%) than boys (44.44%) had HOMA-IR above 3.16 and had elevated FI levels (70.59% vs 48.89%). The difference in the frequency of insulin resistance among obese versus severely obese children and adolescents was not significant (p = 0.73, p > 0.05). Our study results also showed positive, but weak, correlation of HOMA-IR with age, FPG, TG and BMI of the participants (p < 0.05).

CONCLUSION:

Higher percentage of insulin-resistant participants was of female gender and was adolescents. In general, insulin resistant obese children and adolescents tend to have a worse metabolic profile in comparison to individuals without insulin resistance. It is of note that the highest insulin resistance was also linked with the highest concentrations of triglycerides.

Growth and Puberty in Obese Children and Implications of Body Composition

Childhood obesity is a major public health concern throughout the world. Nutrition, energy balance and hormones interplay in growth and pubertal development regulation. Frequently overweight and obese children are taller for their age and sex and tend to mature earlier than lean children. The increased leptin and sex hormone levels seen in obese children with excessive adiposity may be implicated in accelerated pubertal growth and accelerated epiphyseal growth plate maturation. Efforts to detect the impact of obesity in children are needed to prevent metabolic and cardiovascular disease in later life. This review aims to cover the process of growth in obese children and implications of body composition on growth and pubertal development and introduce the use of body composition charts in clinical practice.

Type 2 diabetes in a 5-year-old and single center experience of type 2 diabetes in youth under 10

The worrisome rise in pediatric type 2 diabetes (T2DM) is most prevalent among minority ethnic/racial populations. Typically, T2DM occurs during puberty in high risk obese adolescents with evidence of insulin resistance. Screening for T2DM in obese youth can be a daunting task for pediatricians and differentiating between pediatric T1DM and T2DM in obese youth can be challenging for pediatric endocrinologists. There is very limited data regarding the prevalence of T2DM among youth < 10 years of age. Here we present the case of a 5-year-old Hispanic male diagnosed with T2DM after referral by his pediatrician for abnormal weight gain, acanthosis nigricans and an elevated HbgA1c. He subsequently became symptomatic for diabetes with confirmed hyperglycemia and HbgA1c of 9.7% (83 mmol/mol) at the time of formal diagnosis. Type 1 diabetes autoantibodies (GAD65, Islet, and ZincT8) and monogenic diabetes genetic tests were negative. Due to elevated liver enzymes and baseline HbgA1c, he received basal insulin as his initial therapy. In this paper, we will discuss this case and present an IRB approved retrospective review of the characteristics of the 20 T2DM patients <10 years of age identified to date in our pediatric diabetes center. This review highlights that while uncommon, the diagnosis of T2DM merits consideration even in prepubertal children. This is especially true when working with a high risk population, such as our Hispanic South Texas youth.

Obesity Cardiometabolic Comorbidity Prevalence in Children in a Rural Weight-Management Program

This descriptive study examines the prevalence of obesity-related cardiometabolic (CM) risk factors using CM laboratory metrics, in 3 to 19 year olds presenting to a rural American Academy of Pediatrics stage 3 multidisciplinary weight management clinic based on gender, age ranges, and obesity classes. From 2009 to 2016, 382 children (body mass index ≥85th percentile) enrolled. Multiple logistic regression determined the effects of age, gender, or obesity class on CM risk factors. Odds of elevated insulin were more significant in 15 to 19 year olds than in 3 to 5 year olds, or in 6 to 11 year olds. Obesity class III had higher odds than class II, class I, and overweight in having elevated insulin; twice likely than class II for having low high-density lipoprotein; and twice as likely than class I for high triglycerides. Adolescents and obesity class III categories have significant CM risk but the burden in younger and less severe obesity cohorts cannot be underestimated.

An update on the assessment and management of metabolic syndrome, a growing medical emergency in paediatric populations

In the last decades the increasing rate of obesity in children and adolescents worldwide has led to the onset in paediatric age of metabolic syndrome, a disease commonly associated to adulthood. Central obesity, dyslipidaemia, hyperglycaemia, and hypertension are typical features of metabolic syndrome that seem to hesitate often in type 2 diabetes, cardiovascular disease, non-alcoholic fatty liver disease, and many other clinical conditions. Thus preventing and curing metabolic syndrome in paediatric patients is becoming an urgent need for public health. While diagnostic criteria and therapy of metabolic syndrome in adults are very well defined, there is no consensus on the definition of metabolic syndrome in children and adolescents as well as on healing approaches. The aim of this review is to describe the recent advances on the pathogenesis and clinical outcomes of paediatric metabolic syndrome. We then detail the therapeutic strategies (i.e. dietary regimens, physical exercise, nutraceuticals, and medications) employed to manage the disease. Finally, we analyse the safety profile of the drugs used in children and adolescents by performing a retrospective review of paediatric adverse reactions reported in the FDA's Adverse Event Reporting System database.

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.

The response of circulating omentin-1 concentration to 16-week exercise training in male children with obesity

OBJECTIVES

The purpose of the present study was to investigate the effects of the 16-week exercise training program on serum omentin-1 in relation to change in insulin resistance in obese male children.

METHODS

Thirty-two obese male children, aged 9-12 years, were randomly assigned into Exercise Group (ExG; n = 16) and Control Group (CG; n = 16). ExG participated in a 16-week exercise training program which combined various forms of aerobic activities and resistance training. Body composition, body mass index (BMI), waist circumference (WC), fasting glucose and insulin, homeostasis model assessment estimate of insulin resistance (HOMA2-IR), blood lipids and serum omentin-1 were assessed before and after 16 weeks of training.

RESULTS

Exercise training significantly decreased body mass (7.5%), BMI (7.6%), WC (4.3%), body fat % (15%), fasting insulin (18.5%), total cholesterol (TC) (5.4%), low-density lipoprotein cholesterol (LDL-C) (17%) and triglyceride (TG) (7.4%) compared to CG. Between-groups comparison showed a considerable exercise-induced upregulation in omentin-1 (ES = 89; P < 0.05) levels. Furthermore, in ExG serum omentin-1 levels were significantly increased from 24.5 ± 8.4 to 35.9 ± 9.3 ng/ml (45%; P < 0.001) after the training program, which was accompanied with significantly decreased fasting insulin (P < 0.001). The changes in omentin-1 concentrations correlated with the changes in BMI (r = -0.67, P < 0.001), WC (r = -0.62, P = 0.002), body fat % (r = -0.50, P = 0.004), insulin (r = -0.65, P = 0.001), HOMA2-IR (r = -0.60, P = 0.004), TC (r = -0.53, P = 0.004) and LDL-C (r = -0.51, P = 0.004) in ExG. BMI (β = -0.50, P = 0.009) and fasting insulin (β = -0.54, P = 0.006) changes were found to be independent predictors of omentin-1 increment in multiple regression analysis.

CONCLUSION

Exercise training resulted in a significant increase in serum omentin-1 concentrations in children with obesity. The findings suggest that exercise-induced changes in omentin-1 may be associated with the beneficial effects of exercise on reduced insulin and weight lost.

Metabolic Syndrome: Bridging the Gap from Childhood to Adulthood

Childhood and adolescence are particularly vulnerable periods of life to the effects of cardiometabolic risk and later development of atherosclerosis, hypertension, and diabetes mellitus. Developing countries with limited resources suffer most heavily from the consequences of cardiometabolic risk in children and its future implications to the global health burden. A better understanding of mechanisms leading to cardiometabolic risk in early life may lead to more effective prevention and intervention strategies to reduce metabolic stress in children and later disease. Longitudinal "tracking" studies of cardiometabolic risk in children provide a tremendous global resource to direct prevention strategies for cardiovascular disease. In this review, we will summarize the pathophysiology, existing definitions for cardiometabolic risk components in children. Screening and identifying children and adolescents of high cardiometabolic risk and encouraging them and their families through healthy lifestyle changes should be implemented to as a global public health strategy.

Association between insulin resistance and estrogen in sexual precocity of obese children

The aim of the study was to examine the association between sexual precocity and high-molecular weight (HMW)-adiponectin and investigate the correlation of insulin resistance and estrogen levels in obese children. In total, 60 obese children (30 boys and 30 girls) with sexual precocity were included in group A, 60 obese children (30 boys and 30 girls) without sexual precocity were included in group B, and 60 average weight children (30 boys and 30 girls) were included in group C. The levels of HMW adiponectin, fasting blood glucose, fasting insulin, luteinizing hormone (LH) peak, estradiol and testosterone were measured. The results showed that the HMW-adiponectin level of group A was the lowest and that of group C was the highest. The difference was statistically significant (P<0.05). The homeostasis model assessment of insulin resistance (HOMA-IR) and estradiol levels of group A were significantly higher than those of group B, and group B was higher than that of group C. LH peak and testosterone levels of group A were the lowest while those of group C were the highest. The differences were statistically significant (P<0.05). A subgroup analysis showed that the above results were more significant in girls. The Pearson correlation analysis revealed that the level of HMW-adiponectin was negatively correlated with HOMA-IR and estradiol (P<0.05), and positively correlated with the LH peak (P<0.05). In conclusion, sexual precocity of obese children may be associated with insulin resistance, and the link may be HMW-adiponectin.

The cutoff values of indirect indices for measuring insulin resistance for metabolic syndrome in Korean children and adolescents

PURPOSE

The prevalence rates of metabolic syndrome (MetS) and percentile distribution of insulin resistance (IR) among Korean children and adolescents were investigated. The cutoff values of IR were calculated to identify high-risk MetS groups.

METHODS

Data from 3,313 Korean subjects (1,756 boys and 1,557 girls, aged 10-18 years) were included from the Korean National Health and Nutrition Examination Survey conducted during 2007-2010. Three different sets of criteria for MetS were used. Indirect measures of IR were homeostasis model assessment (HOMA-IR) and triglyceride and glucose (TyG) index. The cutoff values of the HOMA-IR and TyG index were obtained from the receiver operation characteristic curves.

RESULTS

According to the MetS criteria of de Ferranti el al., Cook et al., and the International Diabetes Federation, the prevalence rates in males and females were 13.9% and 12.3%, 4.6% and 3.6%, and 1.4% and 1.8%, respectively. Uses these 3 criteria, the cutoff values of the HOMA-IR and TyG index were 2.94 and 8.41, 3.29 and 8.38, and 3.54 and 8.66, respectively. The cutoff values using each of the 3 criteria approximately corresponds to the 50th-75th, 75th, and 75th-90th percentiles of normal HOMA-IR and TyG index levels.

CONCLUSION

This study describes the prevalence rates of MetS in Korean children and adolescents, an index of IR, and the cutoff values for MetS with the aim of detecting high-risk groups. The usefulness of these criteria needs to be verified by further evaluation.

Use of the triglyceride to HDL cholesterol ratio for assessing insulin sensitivity in overweight and obese children in rural Appalachia

BACKGROUND

Studies have suggested that triglyceride to HDL-cholesterol ratio (TRG/HDL) is a surrogate marker of insulin resistance (IR), but information regarding its use in pediatric patients is limited. This study investigated the ability of TRG/HDL ratio to assess IR in obese and overweight children.

METHODS

The sample consisted of de-identified electronic medical records of patients aged 10-17 years (n=223). Logistic regression was performed using TRG/HDL ratio as a predictor of hyperinsulinemia or IR defined using homeostasis model assessment score.

RESULTS

TRG/HDL ratio had limited ability to predict hyperinsulinemia (AUROC 0.71) or IR (AUROC 0.72). Although females had higher insulin levels, male patients were significantly more likely to have hypertriglyceridemia and impaired fasting glucose.

CONCLUSIONS

TRG/HDL ratio was not adequate for predicting IR in this population. Gender differences in the development of obesity-related metabolic abnormalities may impact the choice of screening studies in pediatric patients.

Metabolic Syndrome in Children and Adolescents: a Critical Approach Considering the Interaction between Pubertal Stage and Insulin Resistance

Pediatricians increasingly diagnose the metabolic syndrome (MetS) in recent years to describe cardiovascular risk and to guide management of the obese child. However, there is an ongoing discussion about how to define the MetS in childhood and adolescence. Since insulin resistance-the major driver of MetS-is influenced by pubertal stage, it is questionable to use definitions for MetS in children and adolescents that do not take into account pubertal status. A metabolic healthy status in prepubertal stage does not predict a metabolic healthy status during puberty. Furthermore, cardiovascular risk factors improve at the end of puberty without treatment. However, having a uniform internationally accepted definition of the MetS for children and adolescents would be very helpful for the description of populations in different studies. Therefore, the concept of MetS has to be revisited under the influence of puberty stage.

Risk Factors for Hyperglycemia During Chemotherapy for Acute Lymphoblastic Leukemia Among Taiwanese Children

BACKGROUND

Hyperglycemia is common during treatment for pediatric acute lymphoblastic leukemia (ALL). Several risk factors have been proposed, but emergence of new evidence suggests conflicting results. In view of ethnic differences in the propensity for diabetes, this study aims to delineate the characteristics of pediatric patients at risk for hyperglycemia during chemotherapy in Taiwan.

METHODS

This retrospective study involved chart review of consecutive patients younger than 18 years with diagnosis of ALL in a medical center in Taiwan from 1997 to 2008. Hyperglycemia was defined by random plasma glucose levels ≥200 mg/dL or fasting glucose levels ≥126 mg/dL in at least two separate samplings. Risk factors for hyperglycemia were described with crude and adjusted odds ratios (OR) with 95% confidence intervals (CI) in the univariate and multivariate regression analysis.

RESULTS

A total of 133 patients were included for analysis. Overall, 22 patients (16.5%) experienced hyperglycemia during ALL treatment. Most hyperglycemic episodes occurred within the first 8 days after prednisolone use. Age older than 10 years was the most important predictor of hyperglycemia (adjusted OR = 10.88, 95% CI 2.40-49.37). Patients with fasting glucose concentration ≥100 mg/dL were also 5.7-fold (95% CI 1.63-19.93) more likely to develop hyperglycemia, whereas the predictive significance of obesity was attenuated after adjustment.

CONCLUSION

Assessment of glucose concentration should be vigilant in the 1(st) week after prednisolone use during ALL treatment. Clinicians should be alert to the patient at risk of hyperglycemia, particularly obese adolescents with disarranged glucose homeostasis.

Differences in Cardiometabolic Risk between Insulin-Sensitive and Insulin-Resistant Overweight and Obese Children

BACKGROUND

It is known that 15-30% overweight/obese adults do not suffer cardiometabolic consequences. There is limited literature examining factors that can be used to assess cardiometabolic health in overweight/obese children. If such factors can be identified, they would aid in differentiating those most in need for aggressive management.

METHODS

Baseline data from 7- to 12-year-old, overweight, and obese children enrolled in a weight management program at an urban hospital were analyzed. Homeostatic model assessment for insulin resistance (HOMA-IR) <2.6 was used to define insulin-sensitive and HOMA-IR ≥2.6 was used to defined insulin-resistant participants. Demographics, physical activity measures, and cardiometabolic risk factors were compared between the two phenotypes. Odds ratios (ORs) examining the association between intermediate endpoints (metabolic syndrome [MetS], nonalcoholic fatty liver disease [NAFLD], systemic inflammation, and microalbuminuria) and the two metabolic phenotypes were evaluated.

RESULTS

Of the 362 overweight/obese participants, 157 (43.5%) were insulin sensitive and 204 (56.5%) were insulin resistant. Compared to the insulin-sensitive group, the insulin-resistant group was older (8.6±1.6 vs. 9.9±1.7; p<0.001) and had a higher BMI z-score (1.89±0.42 vs. 2.04±0.42; p=0.001). After multivariable adjustment, compared to the insulin-sensitive group, the insulin-resistant group had higher odds of having MetS (OR, 5.47; 95% confidence interval [CI]: 1.72, 17.35; p=0.004) and NAFLD (OR, 8.66; 95% CI, 2.48, 30.31; p=0.001), but not systemic inflammation (OR, 1.06; 95% CI: 0.56, 2.03; p=0.86) or microalbuminuria (OR, 1.71; 95% CI, 0.49, 6.04; p=0.403).

CONCLUSIONS

Using a HOMA-IR value of ≥2.6, clinical providers can identify prepubertal and early pubertal children most at risk. Focusing limited resources on aggressive weight interventions may lead to improvement in cardiometabolic health.

Impact of BMI on gonadorelin-stimulated LH peak in premenarcheal girls with idiopathic central precocious puberty

OBJECTIVE

To clarify the impact of body mass index (BMI) on luteinizing hormone (LH) secretion in response to gonadorelin (GnRH) stimulation testing in girls diagnosed with idiopathic central precocious puberty (ICPP).

METHODS

Retrospective single-center cohort study was carried out in 865 confirmed ICPP girls who underwent GnRH stimulation tests. Pubertal development according to Tanner, sex hormone parameters, and LH secretion in response to GnRH-stimulation was compared.

RESULTS

Around 609 girls were of normal weight (70.4%), while 168 children (19.4%) were overweight, and 88 (10.2%) were obese. Peak LH levels after GnRH were much higher in the normal-weight group, with a median of 9.1 mIU ml(-1) (interquartile 5.2-13.1), compared with the median peak LH in the overweight and obese groups (8.5 mIU ml(-1), interquartile 5.3-11.6, and 6.2 mIU ml(-1), interquartile 5.3-11.0, respectively P < 0.001 for all comparisons). Peak LH/FSH ratio was also lower in the obese group (median 0.6, interquartile 0.68-0.90) compared with the normal-weight (median 0.8, interquartile 0.61-1.11) and overweight (median 0.8, interquartile 0.64-0.92) groups.

CONCLUSIONS

Higher BMI is associated with lower LH response to GnRH-stimulation testing in girls with ICPP. It is recommended that BMI should be considered when interpreting GnRH-stimulation tests.

Cardiometabolic risk factors and insulin resistance in obese children and adolescents: relation to puberty

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

The prevalence of obesity with concomitant increasing risk for having cardiometabolic diseases is rising in the childhood population. Insulin resistance has a key role in metabolic changes in these children. Insulin levels elevate as puberty commences in every individual.

WHAT THIS STUDY ADDS

Children with increased risk for cardiometabolic diseases show significant differences in insulin levels even before the onset of puberty compared with those without risks. The pattern of appearance of dyslipidaemia also varies in children with risk factors even in the pre-pubertal group from those without risk. Children with metabolic syndrome display considerably pronounced changes in their metabolic parameters before the onset of puberty, which become more pronounced as puberty passes.

BACKGROUND

Insulin resistance (IR) has a key role in the metabolic changes in obese children. In commencing puberty, the insulin levels elevate. It is not clear, however, how insulin levels develop if the metabolic syndrome appears.

OBJECTIVES

Metabolic changes were assessed in obese children before, during and after puberty to analyse the relationship between IR and puberty in subjects with and without metabolic syndrome.

METHODS

Three hundred thirty-four obese children (5-19 years) attended the study. The criteria of the International Diabetes Federation were used to assess the presence of cardiometabolic risks (CMRs). Subjects with increased CMR were compared with those without risk (nCMR). Pubertal staging, lipid levels, plasma glucose and insulin levels during oral glucose tolerance test were determined in each participant. IR was expressed by homeostasis model assessment (HOMA-IR) and the ratio of glucose and insulin areas under the curve (AUC-IR).

RESULTS

Significantly higher AUC-IR were found in pre-pubertal CMR children compared with nCMR subjects (11.84 ± 1.03 vs. 8.00 ± 0.69; P < 0.01), but no difference was discovered during and after puberty. HOMA-IR differs between CMR and nCMR only in post-puberty (6.03 ± 1.26 vs. 2.54 ± 0.23; P < 0.01). CMR children have dyslipidaemia before the onset of puberty.

CONCLUSIONS

CMR is associated with increased postprandial IR in pre-pubertal and increased fasting IR in post-pubertal obese children. Dyslipidaemia appeared already in pre-puberty in CMR children.

Mood and its association with metabolic health in adolescents: a longitudinal study, EarlyBird 65

BACKGROUND

Mood comprises two main traits - positive and negative affect, both associated with depression and anxiety. Studies in children have linked depression with obesity, but the association with metabolic health is unclear.

OBJECTIVE

To explore the relationship between mood and metabolic health in adolescents.

METHODS

We studied 208 healthy children (115 boys) enrolled in the longitudinal EarlyBird Diabetes Study, and reviewed at 7 and 16 yr. Participants completed the Positive Affect and Negative Affect Schedule - Child Form (PANAS-C) at 16yr to assess positive and negative affect, together representing mood. Measures at 7 and 16 yr: body mass index (BMI), fat (%; dual energy X-ray absorptiometry), physical activity (accelerometer), metabolic risk z-score comprising homeostasis model assessment-insulin resistance (HOMA-IR), triglycerides, total cholesterol/high density lipoprotein (HDL) ratio and blood pressure. Pubertal development was determined by age at peak height velocity.

RESULTS

Positive affect was higher in boys than girls, (50 vs. 46, p = 0.001), negative affect higher in girls than boys (26 vs. 22, p < 0.001). Those with lower mood were fatter (r = -0.24, p < 0.001), had higher HOMA-IR (r = -0.12, p = 0.05), higher cholesterol:HDL ratio (r = -0.14, p = 0.02), were less active (r = 0.20, p = 0.003) and had earlier pubertal development (r = 0.19, p = 0.004). Inverse associations between mood and metabolic risk z-score and change in metabolic risk z-score 7-16yr (β = -0.26, p = 0.006, and -0.40, p = 0.004, respectively) were independent of adiposity, physical activity and puberty and sex.

CONCLUSIONS

Low mood in healthy children is associated with poorer metabolic health independently of adiposity. These findings may have implications for the physical and mental health of contemporary youngsters, given their increasing obesity and cardiometabolic risk.

Metabolic syndrome in children and adolescents from Mérida city, Venezuela: Comparison of results using local and international reference values (CREDEFAR study)

OBJECTIVE

To obtain local reference values for blood lipids and blood pressure (BP), and to determine the prevalence of metabolic syndrome (MS) in children and adolescents from Mérida, Venezuela, and to compare results using local and international cut-off values.

MATERIALS AND METHODS

The study enrolled 916 participants of both sexes aged 9-18 years of age from educational institutions. Demographic, anthropometric, and BP data were collected. Fasting blood glucose and lipid profile were measured. Percentile distribution of lipid and BP values was done by age group and sex. Prevalence of MS was estimated based on the NCEP-ATPIII classification (as modified by Cook et al.) and the classification of the International Diabetes Federation, using percentiles of Mérida and the USA as cut-off points. Agreement between both classifications was estimated using the kappa test (κ).

RESULTS

Prevalence of MS was 2.2% by Cook-Merida percentiles, as compared to 1.8% by Cook-USA percentiles, a moderate agreement (κ=0.54). Agreement between Cook et al. and IDF using Merida percentiles was weak (κ=0.28). There was a higher frequency of abdominal obesity, hypertriglyceridemia and hypertension, and a lower frequency of low HDL-C using Mérida percentiles. The risk (odds ratio) of having MS is greater if abdominal obesity exists (OR: 98.63, CI: 22.45-433.35, p=0.0001). MS was significantly more common in obese subjects (18.3%, p=0.0001).

CONCLUSIONS

Prevalence of MS in this sample of children and adolescents was 2.2%. Lipid and BP values were lower in Venezuelan as compared to US, European, and Asian children and adolescents, and similar to those in Latin-American references. Own reference values are required for accurate diagnosis of MS, as well as a worldwide consensus on its diagnostic criteria.

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.

A study of insulin resistance by HOMA-IR and its cut-off value to identify metabolic syndrome in urban Indian adolescents

OBJECTIVE

Insulin resistance (IR) and associated metabolic abnormalities are increasingly being reported in the adolescent population. Cut-off value of homeostasis model of assessment IR (HOMA-IR) as an indicator of metabolic syndrome (MS) in adolescents has not been established. This study aimed to investigate IR by HOMA-IR in urban Indian adolescents and to establish cut-off values of HOMA-IR for defining MS.

METHODS

A total of 691 apparently healthy adolescents (295 with normal body mass index (BMI), 205 overweight, and 199 obese) were included in this cross-sectional study. MS in adolescents was defined by International Diabetes Federation (IDF) and Adult Treatment Panel III (ATP III) criteria. IR was calculated using the HOMA model.

RESULTS

Mean height, waist circumference (WC), waist/hip ratio (WHR), waist/height ratio (WHtR), and blood pressure were significantly higher in boys as compared to girls. The HOMA-IR values increased progressively from normal weight to obese adolescents in both sexes. Mean HOMA-IR values increased progressively according to sexual maturity rating in both sexes. HOMA-IR value of 2.5 had a sensitivity of >70% and specificity of >60% for MS. This cut-off identified larger number of adolescents with MS in different BMI categories (19.7% in normal weight, 51.7% in overweight, and 77.0% in obese subjects) as compared to the use of IDF or ATP III criteria for diagnosing MS. Odds ratio for having IR (HOMA-IR of >2.5) was highest with WHtR (4.9, p p<0.0001) and WC (4.8, p p<0.0001), compared to WHR (3.3, p p<0.0001).

CONCLUSIONS

In Indian adolescents, HOMA-IR increased with sexual maturity and with progression from normal to obese. A HOMA-IR cut-off of 2.5 provided the maximum sensitivity and specificity in diagnosing MS in both genders as per ATP III and IDF criteria.

Circulatory estrogen level protects against breast cancer in obese women

Literary data suggest apparently ambiguous interaction between menopausal status and obesity-associated breast cancer risk based on the principle of the carcinogenic capacity of estrogen. Before menopause, breast cancer incidence is relatively low and adiposity is erroneously regarded as a protective factor against this tumor conferred by the obesity associated defective estrogen-synthesis. By contrast, in postmenopausal cases, obesity presents a strong risk factor for breast cancer being mistakenly attributed to the presumed excessive estrogen-production of their adipose-tissue mass. Obesity is associated with dysmetabolism and endangers the healthy equilibrium of sexual hormone-production and regular menstrual cycles in women, which are the prerequisites not only for reproductive capacity but also for somatic health. At the same time, literary data support that anovulatory infertility is a very strong risk for breast cancer in young women either with or without obesity. In the majority of premenopausal women, obesity associated insulin resistance is moderate and may be counteracted by their preserved circulatory estrogen level. Consequently, it is not obesity but rather the still sufficient estrogen-level, which may be protective against breast cancer in young adult females. In obese older women, never using hormone replacement therapy (HRT) the breast cancer risk is high, which is associated with their continuous estrogen loss and increasing insulin-resistance. By contrast, obese postmenopausal women using HRT, have a decreased risk for breast cancer as the protective effect of estrogen-substitution may counteract to their obesity associated systemic alterations. The revealed inverse correlation between circulatory estrogen-level and breast cancer risk in obese women should advance our understanding of breast cancer etiology and promotes primary prevention measures. New patents recommend various methods for the prevention and treatment of obesity-related systemic disorders and the associated breast cancer.

A controlled study of lifestyle treatment in primary care for children with obesity

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Lifestyle intervention is the most common treatment strategy for children with obesity. Specialized units for the care of children with obesity report significant effects of lifestyle treatment. In children, the physical activity component in lifestyle treatment is often well accepted.

WHAT THIS STUDY ADDS

Two lifestyle treatment programmes in primary care for children with obesity both gave a reduction of body mass index significantly greater than the change observed in a non-intervention comparison group of children with obesity. Substituting one-third of nurse-led treatment sessions with sessions led by physiotherapists in one of the programmes did not improve the outcome. The efficacy of treatment in primary care seems to be comparable to that reported in the literature.

OBJECTIVE

To evaluate the efficacy of lifestyle treatment in primary care for children with obesity.

METHODS

In a multicentre study, sixty-four 9- to 13-year-old children with obesity were randomized to one of two 12-month lifestyle treatment programmes. The only difference between the programmes was that a physiotherapist substituted the nurse in one-third of the sessions in an attempt to stimulate physical activity. For comparison, children with normal weight and overweight, and an age-, sex- and body mass index-matched non-intervention group of children with obesity were used.

RESULTS

Anthropometry and laboratory data differed significantly between children with obesity and normal weight at baseline. The follow-up at the end of treatment was attended by 55 children with obesity, 28 and 27 in each treatment arm. The mean (standard deviation) body mass standard deviation score changed by -0.36 (0.3) in the arm involving a physiotherapist and by -0.33 (0.2) in the other arm. These outcomes were not significantly different. Both reductions were significantly greater than the change of -0.14 (0.3) observed in the non-intervention comparison group of children with obesity

CONCLUSION

The efficacy of treatment in primary care for children with obesity seems to be comparable to that reported in the literature. ISRCTN44919688.

Intramyocellular lipid is associated with visceral adiposity, markers of insulin resistance, and cardiovascular risk in prepubertal children: the EPOCH study

CONTEXT

The intramyocellular deposition of lipid associates with metabolic dysregulation in adolescents and adults. Relatively little is known about the deposition of fat in muscle before the onset of puberty.

OBJECTIVE

Our objective was to describe the relationship between intramyocellular lipid (IMCL) accumulation and 1) visceral adiposity and 2) markers of insulin resistance and cardiovascular disease risk in a cohort of prepubertal and early pubertal children.

STUDY DESIGN

Data were collected as part of a retrospective cohort study, Exploring Perinatal Outcomes among Children (EPOCH). Multiple linear regression models were constructed for data analysis.

RESULTS

A total of 441 children participated in the study (226 prepubertal, 215 early pubertal). In prepubertal children, there was a significant relationship between IMCL and visceral fat (parameter estimate 0.019, P = 0.002) that remained after controlling for body mass index. Independent of overall adiposity, in all children, IMCL was associated with the triglyceride to high-density lipoprotein ratio (parameter estimate 0.1418, P = 0.002).

CONCLUSIONS

This study demonstrates a concerning and related pattern of IMCL and visceral fat deposition in prepubertal children. Intramuscular fat deposition is linked to markers of insulin resistance and cardiovascular disease risk.

[Correlation between insulin resistance and puberty in children with increased cardiometabolic risk]

Epidemiologic data provide evidence that the frequency of obesity and cardiometabolic risk factors shows an increasing tendency in childhood. Insulin resistance plays a central role in the pathogenesis of cardiovascular and metabolic consequences of obesity. Transient decrease in the insulin sensitivity during puberty is a well-known physiological process; however, the feature of this phenomenon is not clear in obese children with increased cardiometabolic risk.

AIM

The aim of the present study was to assess the effect of puberty on insulin resistance and metabolic parameters in obese children with and without increased cardiometabolic risk.

MATERIALS AND METHODS

Anthropometric data, insulin levels during oral glucose tolerance test and lipid status were analyzed of 161 obese children aged 4-18 years. Σinsulin/Σglucose ratio was obtained during glucose load and HOMA index was used to assess insulin resistance. Children were sorted into prepubertal (T1), pubertal (T2-4) and postpubertal (T5) cohorts according to Tanner staging criteria and metabolic and insulin resistance parameters were evaluated. Increased cardiometabolic risk was defined as the presence of any two risk factors (elevated fasting plasma glucose, blood pressure, triglyceride or decreased HDL-cholesterol) in addition to obesity.

RESULTS

Out of 161 obese subjects, 43 (26.7%) had increased cardiometabolic risk. Decreased HDL-cholesterol and/or elevated triglyceride was observed in 101 (56.5%) cases. Impaired glucose tolerance and/or impaired fasting glucose was found in 23 (14.4%) cases. In subjects without increased cardiometabolic risk, the Σinsulin/Σglucose ratio in T1 stage was significantly lower than in T2-4 and T5 stages (p = 0.01). In children with increased cardiometabolic risk, the insulin/glucose ratio was similar in T1, T2-4 and T5 stages, however, it was significantly higher in T1 stage as compared to subjects without increased cardiometabolic risk (p = 0.04). In T2-4 and T5 stages, Σinsulin/Σglucose ratio did not differ between children with and without increased cardiometabolic risk. No difference was found in HOMA index between groups with and without increased cardiometabolic risk in T1 stage, however significantly higher levels were observed in subjects with increased cardiometabolic risk at T2-4 stages (p = 0.01), indicating the presence of fasting hyperinsulinemia in this cohort. Elevated HbA1c (≥6.0%) was found in 13 (16%) out of the 81 children investigated, of whom only two cases had abnormal oral glucose tolerance test. In cases having normal HbA1c, oral glucose tolerance test showed impaired glucose tolerance in 5 cases, impaired fasting glucose in 2 cases, both impaired glucose tolerance and impaired fasting glucose in 2 cases, and type 2 diabetes in 2 cases.

CONCLUSION

Increased insulin resistance can be observed in obese children without increased cardiometabolic risk. In obese children with increased cardiometabolic risk, substantial insulin resistance occurs in prepuberty and it is present at similar level throughout puberty. Fasting insulin levels are elevated in obese subjects with increased cardiometabolic risk as compared to those without increased cardiometabolic risk. To reveal type 2 diabetes cases, HbA1c and oral glucose tolerance test results should be assessed parallel.

Prevalence of metabolic syndrome in obese children and adolescents using three different criteria and evaluation of risk factors

OBJECTIVE

To compare the prevalence of the metabolic syndrome (MS) in Turkish obese children and adolescents by using three different definitions and to assess the risk factors through a retrospective evaluation of anthropometric and laboratory parameters.

METHODS

Sixty hundred and fourteen obese patients (307 male, 307 female; mean age: 11.3±2.5 years) were included in the study. Medical history, physical examination, anthropometric measurements, results of biochemical and hormonal assays were obtained from the hospital records. MS was diagnosed according to the modified World Health Organization (WHO), Cook and the International Diabetes Federation (IDF) consensus criteria.

RESULTS

The prevalence of MS was found to be 39%, 34% and 33% according to the modified WHO, Cook and the IDF consensus criteria, respectively. MS prevalence in patients aged 12-18 years was significantly higher than that in patients between 7 and 11 years of age (p<0.05). Pubertal patients had a significantly higher MS prevalence than the non-pubertal cases (p<0.05). MS prevalence was also significantly higher in children who had a family history of heart disease, diabetes, obesity and hypertension as well as in those who had not been breast-fed (p<0.05).

CONCLUSION

The use of the modified WHO criteria was found to result in a slightly higher prevalence rate for MS as compared to the other criteria. The prevalence of MS in our study population was higher than that reported in most previous studies in Turkey. A positive family history, puberty and not being breastfed in infancy were shown to be significant risk factors for MS in childhood.

Metabolic syndrome: definitions and controversies

Metabolic syndrome (MetS) is a complex disorder defined by a cluster of interconnected factors that increase the risk of cardiovascular atherosclerotic diseases and diabetes mellitus type 2. Currently, several different definitions of MetS exist, causing substantial confusion as to whether they identify the same individuals or represent a surrogate of risk factors. Recently, a number of other factors besides those traditionally used to define MetS that are also linked to the syndrome have been identified. In this review, we critically consider existing definitions and evolving information, and conclude that there is still a need to develop uniform criteria to define MetS, so as to enable comparisons between different studies and to better identify patients at risk. As the application of the MetS model has not been fully validated in children and adolescents as yet, and because of its alarmingly increasing prevalence in this population, we suggest that diagnosis, prevention and treatment in this age group should better focus on established risk factors rather than the diagnosis of MetS.

High HOMA-IR, adjusted for puberty, relates to the metabolic syndrome in overweight and obese Chilean youths

OBJECTIVE

To determine how the homeostasis model assessment of insulin resistance (HOMA-IR) is related to metabolic risk in a sample of overweight and obese Chilean youths accounting for Tanner stage.

METHODS

A cross-sectional study assessing 486 overweight and obese youths (aged 5-15 years) recruited from the University of Chile, Pediatric Obesity Clinic. We measured anthropometry, Tanner stage, HOMA-IR, and laboratory tests related to metabolic risk. HOMA-IR was categorized by quartile for children (Tanner stages I and II) and adolescents (Tanner stage III and above) from a normative Chilean sample.

RESULTS

Children and adolescents with HOMA-IR in the highest quartile were likely to have higher body mass index (BMI) Z-scores, elevated waist circumference, systolic and diastolic blood pressure, and triglycerides and low high-density lipoprotein. HOMA-IR had good negative predictive value for characteristics of the metabolic syndrome (MetS; 0.82). In a multivariate regression model, BMI Z-score [odds ratio (OR) 1.5] and HOMA-IR (OR 3.3) predicted 22% of the variance for the MetS, with 36% of the explained variance attributed to HOMA-IR.

CONCLUSIONS

In a large clinical sample of overweight and obese Chilean youths, HOMA-IR ≥ 75th percentile was significantly associated with the cluster of factors referred to as the MetS. We emphasize the importance of establishing percentiles for HOMA-IR based on a normative sample and taking Tanner stage into account. Although BMI is easy to assess and interpret with minimal costs in a clinical setting, adding HOMA-IR explains more of the variance in the MetS than BMI Z-score alone.

Obesity and the pubertal transition in girls and boys

Childhood obesity has become a major health concern in recent decades, especially with regard to metabolic abnormalities that impart a high risk for future cardiovascular disease. Recent data suggest that excess adiposity during childhood may influence pubertal development as well. In particular, excess adiposity during childhood may advance puberty in girls and delay puberty in boys. Obesity in peripubertal girls may also be associated with hyperandrogenemia and a high risk of adolescent polycystic ovary syndrome. How obesity may perturb various hormonal aspects of pubertal development remains unclear, but potential mechanisms are discussed herein. Insulin resistance and compensatory hyperinsulinemia may represent a common thread contributing to many of the pubertal changes reported to occur with childhood obesity. Our understanding of obesity's impact on pubertal development is in its infancy, and more research into pathophysiological mechanisms and longer-term sequelae is important.