Alterations of carbohydrate and lipoprotein metabolism in childhood obesity--impact of insulin resistance and acanthosis nigricans

Physical Examination Findings Among Children and Adolescents With Obesity: An Evidence-Based Review

Overweight and obesity affects 1 in 3 US children and adolescents. Clinical recommendations have largely focused on screening guidelines and counseling strategies. However, the physical examination of the child or adolescent with obesity can provide the clinician with additional information to guide management decisions. This expert-based review focuses on physical examination findings specific to children and adolescents with obesity. For each physical examination element, the authors define the finding and its prevalence among pediatric patients with obesity, discuss the importance and relevance of the finding, describe known techniques to assess severity, and review evidence regarding the need for additional evaluation. The recommendations presented represent a comprehensive review of current evidence as well as expert opinion. The goal of this review is to highlight the importance of conducting a targeted physical examination during pediatric weight management visits.

Acanthosis nigricans, vitamin D, and insulin resistance in obese children and adolescents

OBJECTIVES

The aim of this study is to identify factors accounting for the variation in 25-hydroxyvitamin D levels in a pediatric obese population.

PATIENTS AND METHODS

One hundred and forty-nine obese children and adolescents (BMI ≥95th percentile) were evaluated in a pediatric endocrine office. Acanthosis nigricans (AN) skin lesions were rated on a 4-point scale.

RESULTS

The 25-hydroxyvitamin D levels were significantly different between those without AN and those with any severity of AN (p=<0.001). Insulin levels were only significantly different between those with no and severe AN (p=0.007). A general linear model showed that month of visit predicted 19.0% of the variation and AN an additional 2.2%. When AN was dropped from the full model, log-transformed HOMA-IR remained insignificant (p=0.164).

CONCLUSIONS

Season of evaluation was the main determinant of 25-hydroxyvitamin D levels. Severity of AN was a stronger predictor of 25-hydroxyvitamin D level variation than the measure of insulin resistance HOMA-IR.

Prevalence of insulin resistance and impaired glucose tolerance in a sample of obese Spanish children and adolescents

The prevalence of obesity in children has increased in developed countries in the last decades. It is associated with alterations in glucose metabolism that may be present in childhood. To assess the frequency of glucose metabolism alterations and insulin resistance and their possible determinants in a sample of obese children from Valladolid (Spain), we retrospectively studied 100 obese children and adolescents (11.59 ± 2.73 years). Anthropometric measures, biochemical parameters, and oral glucose tolerance test (OGTT) were performed. Insulin resistance was evaluated with fasting insulin, HOMA index, and insulin values in OGTT. Impaired glucose tolerance was found in 15% of the sample, and was the most frequent of glucose metabolism alterations. Impaired fasting glucose was found in 2%. No case of type 2 diabetes was found. Acanthosis nigricans was present in 22%, with predominance in females, but not all presented insulin resistance. The prevalence of insulin resistance was 29% when HOMA index was used, and 50% when the insulin response in OGTT was used. Not all patients with impaired glucose tolerance had a pathological HOMA index, and not all with pathological HOMA index presented insulin resistance when insulin values in OGTT were used. Higher 2-h post-OGTT insulin levels were found in children with impaired glucose tolerance. It is paramount to identify young people with glucose regulation alterations for early, intensive intervention to prevent or at least postpone the onset of type 2 diabetes. OGTT is a screening tool necessary to fulfill this objective.

Acanthosis nigricans predicts the clustering of metabolic syndrome components in Hispanic elementary school-aged children

BACKGROUND

Acanthosis nigricans (AN) is a dermatologic condition associated with hyperinsulinemia, a marker of insulin resistance that is the principal abnormality in metabolic syndrome (MetS). We examined the association of AN with the clustering of MetS components.

METHODS

A cross-sectional study was conducted in an urban school-based health center in New Mexico. Students without diabetes were evaluated for AN, a family history of type 2 diabetes, body mass index (BMI), and MetS components. The clustering of MetS components by BMI category and AN status was assessed by comparing the group means of summed average z-scores of fasting insulin, triglycerides, high-density lipoprotein-cholesterol, and systolic blood pressure among the students. A multivariate model with BMI category and AN status controlling for Tanner stage was performed to identify the variables associated with the clustering of MetS components.

RESULTS

Complete data were available for 90 children (age, 9.7±1.4 years; 94% Hispanic; 60% female). In multivariate modeling of MetS cluster z-score, significant differences were found between the students with BMI <85th percentile [-0.27; 95% confidence interval (95% CI)=-0.42 to -0.11] and (a) the students with BMI 85th-94.9th percentile with AN (0.74; 95% CI=0.17-1.31) and (b) the students with BMI ≥95th percentile with AN (0.86; 95% CI=0.54-1.18). No significant differences in the MetS cluster z-score were seen between the students with BMI <85th percentile and those with BMI 85th-94.9th percentile without AN (0.24; 95% CI=-0.33 to 0.81) or those with BMI ≥95th percentile without AN (0.31; 95% CI=-0.13 to 0.75).

CONCLUSIONS

Overweight/obese Hispanic elementary school-aged children with AN exhibit clustering of MetS components and could benefit from early intervention.