Biochemical characteristics and risk factors for insulin resistance at different levels of obesity

Hypertension in adolescents: The role of obesity and family history

We evaluated the combined effect of obesity and family history (FH) on the risk of hypertension in adolescents. We studied 1288 school‐aged adolescents aged 16.0 ± 0.5 years (49.0% males) attending the medical examination for enrollment in the city of Nanning, China. Their blood pressure, weight, and height were measured. A questionnaire was administered to both adolescents and their parents to obtain information on the participants’ medical history. Multiple logistic regression analysis, according to bodyweight categories and adjusted for age, gender, and body mass index (BMI), was done to determine the association of FH with hypertension. Hypertension was found in 14.1% of adolescents. The prevalence of hypertension was significantly higher in adolescents with obesity and positive FH than their normal weight and negative FH counterparts. For adolescents with normal weight and waist circumstance (WC), those with a positive FH in parents compared to those without had an significantly increased risk for hypertension (odds ratio [OR], 2.15; 95% confidence interval [CI] 1.28–3.61, and 1.96; 95% CI 1.16–3.32, respectively). These findings were adjusted for age, gender, and BMI. Our study showed that routine screening for pediatric hypertension should be performed in adolescents who are overweight and obese. Furthermore, parental FH of hypertension played an important role in predicting the hypertension phenotype among adolescents with normal weight.

Insulin Resistance as a Diagnostic Criterion for Metabolically Healthy Obesity in Children

OBJECTIVES

In recent years, a subgroup of individuals with obesity has been described as having a lower risk of metabolic and cardiovascular complications. These individuals have what is referred to as metabolically healthy obesity (MHO), which has a favorable metabolic profile and a lower probability of long-term complications. The definition of this subtype in children is not clear. The aim of the present study was to determine whether Homeostasis Model Assessment (HOMA) above a set threshold could be the marker of metabolically unhealthy obesity (MUO) in children, or a parameter that can be used in the overall assessment. It is intended to compare the International Diabetes Federation (IDF) criteria against HOMA in the diagnosis of MUO.

METHODS

This observational, retrospective, cohort study included children with obesity and analyzed their metabolic state by means of blood testing and dual-energy X-ray absorptiometry.

RESULTS

A total of 96 patients were included, 44.8% boys and 55.2% girls, ages 6-17 years. The patients with MHO according to the HOMA criterion were younger (P = 0.001), had a lower body mass index (BMI) z score (P = 0.006), waist-height index (P = 0.009), hip-height index (P = 0.010), blood glucose (P = 0.003), insulin (P < 0.001), and lower percentages of total fat (P = 0.002), trunk fat (P = 0.001), and android fat (P = 0.009) than those with MUO. The logistic regression analysis according to IDF criteria detected an area under the receiver operating characteristic (ROC) curve of 0.659 (95% CI 0.546-0.771; P = 0.009) versus the area under the ROC curve of 0.854 (95% CI 0.777-0.931; P < 0.001) for the HOMA definition. Therefore, the determination of the metabolic state according to HOMA has greater sensitivity and specificity than the IDF criteria. The multivariate analysis in children classified according to HOMA revealed that the percentage of total fat and gynoid fat distributions and triglyceride level could be markers of a healthy or unhealthy metabolic state in children with obesity (P < 0.001).

CONCLUSIONS

The use of HOMA as a single criterion was demonstrated to be an effective and simple detector of adiposity, which predicts the metabolically healthy obesity in children.

Physiological and Lifestyle Traits of Metabolic Dysfunction in the Absence of Obesity

PURPOSE OF REVIEW

Individuals with metabolically unhealthy normal weight (MUNW) have an adverse cardiometabolic risk factor profile in the absence of excess body weight, and increased risk for diabetes and heart disease. We critically review some physiological traits and lifestyle characteristics of the MUNW phenotype.

RECENT FINDINGS

The prevalence of MUNW varies considerably around the world and among ethnicities, partly because of different definitions; on average, this phenotype affects about ~ 30% of normal weight persons globally. Most studies have recruited MUNW subjects who, although within the normal weight range, are significantly "more obese" than their metabolically healthy lean peers (greater body mass index or total body fat); hence one cannot ascertain whether observed differences are true traits of the MUNW phenotype of simply secondary to greater relative adiposity within the normal range. Carefully matched studies have indicated that MUNW can exist in the absence of excess total body fat. These subjects have a preferential accumulation of fat in the upper body (abdominal subcutaneous and visceral adipose tissues) and the liver, but not skeletal muscle; perhaps surprisingly, this predominantly "android" fat distribution does not translate into increased waist circumference. The MUNW phenotype is associated with lower aerobic fitness and muscle mass and strength, but whether this is simply due to inadequate regular physical activity is not entirely clear. Likewise, no consistent associations have been found between any dietary factors and the development of MUNW phenotype, but diet-induced modest weight loss facilitates its resolution. Delineating the mechanisms leading to metabolic dysfunction in the absence of increased body weight and body fat will likely reveal important targets for improving metabolic health and eventually for reducing the burden of cardiometabolic disease, not only in individuals with normal body weight but also in people with obesity.

Determinants of new onset cardiometabolic risk among normal weight children

OBJECTIVE

To identify determinants for the development of "normal weight metabolically unhealthy" (NWMU) profiles among previously metabolically healthy normal weight children.

METHODS

The QUALITY cohort comprises youth 8-10 years of age with a parental history of obesity (n = 630). Of these, normal weight children with no metabolic risk factors were identified and followed up 2 years later (n = 193). Children were classified as NWMU if they remained normal weight but developed at least one cardiometabolic risk factor. They were classified as normal weight metabolically healthy otherwise. Multivariable logistic regression models were used to identify whether adiposity (anthropometrics and DXA), lifestyle habits (physical activity, screen time, vegetables, and fruit- and sugar-sweetened beverages intake), fitness, and family history of cardiometabolic disease were associated with new onset NWMU.

RESULTS

Of the 193 normal weight and metabolically healthy children at baseline, 45 (23%) became NWMU 2 years later (i.e., 48% had elevated HDL cholesterol, 13% had elevated triglycerides, and 4% had impaired fasting glucose). Changes in adiposity between baseline and follow-up were associated with an increased risk of NWMU for all adiposity measures examined (e.g., for ∆zBMI OR = 3.95; 95% CI: 1.76, 8.83). Similarly, a 2-year change in screen time was associated with incident NWMU status (OR = 1.24; 95% CI 1.04, 1.49).

CONCLUSIONS

Children who increase their adiposity levels as they enter puberty, despite remaining normal weight, are at risk of developing cardiometabolic risk factors. Studies examining long-term consequences of NWMU profiles in pediatrics are needed to determine whether changes in screening practice are warranted.

Children With Metabolically Healthy Obesity: A Review

Children with "metabolically healthy obesity" (MHO) are a distinct subgroup of youth with obesity, who are less prone to the clustering of cardiometabolic risk factors. Although this phenotype, frequently defined by the absence of metabolic syndrome components or insulin resistance, was first described during the early 1980s, a consensus-based definition of pediatric MHO was introduced only recently, in 2018. The purpose of this review was to concisely summarize current knowledge regarding the MHO phenomenon in youth. The prevalence of MHO in children varies from 3 to 87%, depending on the definition used and the parameters evaluated, as well as the ethnicity and the pubertal status of the sample. The most consistent predictors of MHO in youth include younger age, lower body mass index, lower waist circumference, and lower body fat measurements. Various hypotheses have been proposed to elucidate the underlying factors maintaining the favorable MHO phenotype. While preserved insulin sensitivity and lack of inflammation were previously considered to be the main etiological factors, the most recent findings have implicated adipokine levels, the number of inflammatory immune cells in the adipose tissue, and the reduction of visceral adiposity due to adipose tissue expandability. Physical activity and genetic factors also contribute to the MHO phenotype. Obesity constitutes a continuum-increased risk for cardiometabolic complications, which is less evident in children with MHO. However, some findings have highlighted the emergence of hepatic steatosis, increased carotid intima-media thickness and inflammatory biomarkers in the MHO group compared to peers without obesity. Screening should be directed at those more likely to develop clustering of cardiometabolic risk factors. Lifestyle modifications should include behavioral changes focusing on sleep duration, screen time, diet, physical activity, and tobacco smoke exposure. Weight loss has also been associated with the improvement of insulin sensitivity and inflammation. Further investigative efforts are needed in order to elucidate the mechanisms which protect against the clustering of cardiometabolic risk factors in pediatric obesity, to provide more efficient, targeted treatment approaches for children with obesity, and to identify the protective factors preserving the MHO profile, avoiding the crossover of MHO to the phenotype with metabolically unhealthy obesity.

Hypertriglyceridemia is associated with impaired fasting glucose in normal-weight children

BACKGROUND

Previous studies have suggested that elevated triglyceride levels may precede the appearance of glucose metabolic disturbances in adults; nonetheless, this hypothesis has not been tested in children. Hence, we evaluated whether hypertriglyceridemia is associated with impaired fasting glucose (IFG) in normal-weight children.

METHODS

Normal-weight healthy children aged 7-15 years were enrolled in a population-based cross-sectional population study and allocated into groups with and without hypertriglyceridemia. Hypertriglyceridemia was defined by serum triglyceride levels ≥100 and ≥130 mg/dL for children aged 7-9 and 10-15 years, respectively, and IFG by fasting plasma glucose levels ≥100 and <126 mg/dL.

RESULTS

A total of 1453 children with average age of 11.3 ± 2.4 years were enrolled in the study and allocated into the groups with (n = 172) and without (n = 1281) hypertriglyceridemia. In the overall population, the prevalence of hypertriglyceridemia and IFG was 11.8% and 11.2%, respectively. The logistic regression analysis adjusted by age, gender, BMI, waist circumference, and insulin levels showed that hypertriglyceridemia is associated with IFG in children aged 10-15 years (odds ratio (OR) = 1.67; 95% confidence interval (CI): 1.02-2.77, p = 0.04) but not in those aged 7-9 years (OR = 1.48; 95% CI: 0.39-5.58, p = 0.55).

CONCLUSION

Hypertriglyceridemia is associated with IFG in normal-weight children aged 10-15 years, but not in those aged 7-9 years.

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.

The triglycerides and glucose index is associated with cardiovascular risk factors in normal-weight children and adolescents

BackgroundGiven the usefulness of the product of triglycerides and glucose (TyG) to recognize individuals at high risk for developing cardiovascular events, the aim of this study was to determine whether the TyG index is associated with the presence of cardiovascular risk factors in apparently healthy normal-weight children and adolescents.MethodsApparently healthy children and adolescents with normal weight, aged 6-15 years, were enrolled in a population-based cross-sectional study. The children were allocated into groups with and without cardiovascular risk factors. Cardiovascular risk factors were considered as the occurrence of at least one of the following: elevated blood pressure, hypertriglyceridemia, low high-density lipoprotein cholesterol (HDL-C), or hyperglycemia.ResultsA total of 2,117 children and adolescents were enrolled in the study; of them, 1,078 (50.9%) participants exhibited cardiovascular risk. The adjusted logistic regression analysis showed that elevated TyG index was significantly associated with hypertriglyceridemia (odds ratio (OR)=96.45, 95% confidence interval (CI): 48.44-192.04), low HDL-C (OR=2.07, 95% CI: 1.46-2.92), and hyperglycemia (OR=3.11, 95% CI: 2.05-4.72), but not with elevated blood pressure (OR=1.39, 95% CI: 0.89-2.16).ConclusionThe elevated TyG index is associated with the presence of cardiovascular risk factors in healthy normal-weight children and adolescents.

Advanced bone age and hyperinsulinemia in overweight and obese children

OBJECTIVE

In obese children, bone age (BA) tends to significantly exceed chronological age (CA). In vitro studies in mice suggest that insulin may directly modulate skeletal growth. We investigated whether there is an association between fasting insulin and BA maturation in obese children.

METHODS

The study cohort comprised 74 overweight and obese children ages 4 to 13 years. BA divided by CA was used as an index for bone advancement. Participants were classified into tertiles based on their BA:CA ratio. Advanced BA maturation was defined as the third tertile, with BA:CA > 1.21. Components of the metabolic syndrome, including fasting insulin, fasting glucose, triglycerides, and high-density lipoprotein (HDL) levels, were measured.

RESULTS

Children with advanced BA were significantly younger, had a higher body mass index (BMI)-Z score (BMI-Z), and were taller than children with bone advancement in the lower tertiles. Females had a 4.7-fold increased risk for advanced BA compared with males (95% confidence interval [CI], 1.29-17.1; P = .02). Children with a BMI-Z ≥ 1.96 and fasting insulin ≤ 30 μU/L had a 3.6-fold increased risk of advanced BA (95% CI, 1.00-12.8; P = 0.05). Moreover, hyperinsulinemia (fasting insulin > 30 μU/L) was associated with a 6.8-fold increased risk for advanced BA, independent of the degree of obesity (95% CI, 1.45-32.1; P = .01).

CONCLUSION

Marked hyperinsulinemia is associated with advanced BA in obese children. Insulin appears to modulate skeletal growth in humans.

Relationship between elevated triglyceride levels with the increase of HOMA-IR and HOMA-β in healthy children and adolescents with normal weight

To test the hypothesis that mildly elevated triglyceride levels are associated with the increase of homeostasis model assessment of insulin resistance (HOMA-IR) and β-cell function (HOMA-β) indices in healthy children and adolescents with normal weight, we conducted a cross-sectional population study. Based on fasting triglyceride levels, participants were allocated into groups with and without triglyceride levels ≥1.2 mmol/L. Normal weight was defined by body mass index between the 15th and 85th percentiles, for age and gender. Insulin resistance and insulin secretion were estimated using HOMA-IR and HOMA-β indices. A total of 1660 children and adolescents were enrolled, of them 327 (19.7%) with mildly elevated triglycerides. The multivariate linear regression analysis showed that mildly elevated triglyceride levels in children were associated with HOMA-IR (β = 0.214, p < 0.001), HOMA-β (β = 0.139, p = 0.001), systolic (β = 0.094, p = 0.01), and diastolic blood pressure (β = 0.102, p = 0.007), whereas in adolescents, HOMA-IR (β = 0.267, p < 0.001) and HOMA-β (β = 0.154, p < 0.001), but not systolic (β = 0.029, p = 0.38) and diastolic blood pressure (β = 0.015, p = 0.642), showed association with mildly elevated triglycerides.

CONCLUSION

Mildly elevated triglyceride levels are associated with increased HOMA-IR and HOMA-β indices in healthy children and adolescents with normal weight.

Vitamin D supplementation promotes macrophages' anti-mycobacterial activity in type 2 diabetes mellitus patients with low vitamin D receptor expression

The increasing number of people with type 2 diabetes (DM2) is alarming and if it is taken into account that the relative odds of developing tuberculosis in diabetic patients ranges from 2.44 to 8.33 compared with non-diabetic patients, thus in developing countries where these two diseases are encountering face to face, there is a need for prophylaxis strategies. The role of vitamin D has been widely implicated in growth control of Mycobacterium tuberculosis (Mtb) during primary infection mainly through the induction of certain antimicrobial peptides (AMPs). In this study we evaluated the vitamin D serum levels, CYP27B1-hydroxylase enzyme, vitamin D receptor (VDR) and AMPs gene expression in Healthy donors, DM2 and TB patients. Results showed that DM2 group has lower VDR and AMPs expression levels. When Monocytes Derived Macrophages (MDM) from DM2 patients with low VDR expression were supplemented with vitamin D, MDMs eliminate efficiently M. tuberculosis. This preliminary study suggests the use of vitamin D as prophylaxis for tuberculosis in high DM2 endemic countries.

Flavonol-rich dark cocoa significantly decreases plasma endothelin-1 and improves cognition in urban children

Air pollution exposures are linked to systemic inflammation, cardiovascular and respiratory morbidity and mortality, neuroinflammation and neuropathology in young urbanites. In particular, most Mexico City Metropolitan Area (MCMA) children exhibit subtle cognitive deficits, and neuropathology studies show 40% of them exhibiting frontal tau hyperphosphorylation and 51% amyloid-β diffuse plaques (compared to 0% in low pollution control children). We assessed whether a short cocoa intervention can be effective in decreasing plasma endothelin 1 (ET-1) and/or inflammatory mediators in MCMA children. Thirty gram of dark cocoa with 680 mg of total flavonols were given daily for 10.11 ± 3.4 days (range 9–24 days) to 18 children (10.55 years, SD = 1.45; 11F/7M). Key metabolite ratios in frontal white matter and in hippocampus pre and during cocoa intervention were quantified by magnetic resonance spectroscopy. ET-1 significantly decreased after cocoa treatment (p = 0.0002). Fifteen children (83%) showed a marginally significant individual improvement in one or both of the applied simple short memory tasks. Endothelial dysfunction is a key feature of exposure to particulate matter (PM) and decreased endothelin-1 bioavailability is likely useful for brain function in the context of air pollution. Our findings suggest that cocoa interventions may be critical for early implementation of neuroprotection of highly exposed urban children. Multi-domain nutraceutical interventions could limit the risk for endothelial dysfunction, cerebral hypoperfusion, neuroinflammation, cognitive deficits, structural volumetric detrimental brain effects, and the early development of the neuropathological hallmarks of Alzheimer's and Parkinson's diseases.