Prevalence and determinants of insulin resistance among U.S. adolescents: a population-based study

An overview of pediatric obesity

Pediatric obesity is increasing worldwide and disproportionately affects the economically and socially disadvantaged. Obese children are at risk of developing the (dys)metabolic syndrome, insulin resistance, early-onset type 2 diabetes mellitus, polycystic ovarian syndrome, hypertension, hyperlipidemia, and obstructive sleep apnoea. Those with diabetes may have mixed features of type 1 and type 2 diabetes mellitus. Pediatric obesity is the result of persistent adverse changes in food intake, lifestyle, and energy expenditure. It may be because of underlying a genetic syndrome or a conduct disorder. Children living in urban settings often lack safe, affordable, and accessible recreational facilities. Tight educational schedules mean less free time, while computer games and television have become preferred recreational activities. More families are eating out or eating take-out meals and processed foods at home because of pressures of work and time constraints. Consumer advertising targeted at children and the ready availability of vending machines encourage unwise food choices. Some children eat excessively because they are depressed, anxious, sad, or lonely. Often families and obese children are aware of the need for healthy eating and exercise but are unable to translate knowledge into weight loss. Population-based measures such as public education, school meal reforms, child-safe exercise friendly environments, and school-based and community-based exercise programs have been shown to be successful to varying degrees, but there remain individuals who will need special help to overcome obesity. Overeating (e.g. binge eating) may be a manifestation of disordered coping behavior but may also be because of defects in the neural and hormonal control of appetite and satiety. New pharmacological approaches are targeting these areas. We need a coordinated approach involving government, communities, and healthcare providers to provide a continuum of population-based interventions, focused screening, and personalized multidisciplinary interventions for the obese child and family.

A quantitative trait locus on chromosome 13q affects fasting glucose levels in Hispanic children

OBJECTIVE

The prevalence of childhood obesity has increased dramatically in the United States. Early presentation of type 2 diabetes has been observed in children and adolescents, especially in the Hispanic population. The genetic contribution of glucose homeostasis related to childhood obesity is poorly understood. The objective of this study was to localize quantitative trait loci influencing fasting serum glucose levels in Hispanic children participating in the Viva La Familia Study.

DESIGN

Subjects were 1030 children ascertained through an overweight child from 319 Hispanic families. Fasting serum glucose levels were measured enzymatically, and genetic linkage analyses were conducted using SOLAR software.

RESULTS

Fasting glucose was heritable, with a heritability of 0.62 +/- 0.08 (P < 0.01). Genome-wide scan mapped fasting serum glucose to markers D13S158-D13S173 on chromosome 13q (LOD score of 4.6). A strong positional candidate gene is insulin receptor substrate 2, regulator of glucose homeostasis and a candidate gene for obesity. This region was reported previously to be linked to obesity- and diabetes-related phenotypes.

CONCLUSIONS

A quantitative trait locus on chromosome 13q contributes to the variation in fasting serum glucose levels in Hispanic children at high risk for obesity.

The laparoscopic approach toward hyperinsulinism in children

Hyperinsulinemic hypoglycemia (HH) in children requiring surgery is rare. Early HH can be the result of focal or diffuse pancreatic pathology. A number of genetic abnormalities in early HH have been identified, but in the majority of patients no abnormality is found. The sporadic focal and diffuse forms as well the autosomal recessive form are particularly therapy-resistant and demand for early surgery. Preoperative discrimination between focal and diffuse disease in early HH is difficult. 18 F DOPA PET in combination with CT is promising as is laparoscopic exploration of the pancreas. Frozen section biopsy analysis has not been uniformly beneficial. If macroscopically no focal lesion is found, limited laparoscopic distal pancreatectomy provides tissue for definitive pathologic examination. Subsequent near total laparoscopic spleen-saving pancreatectomy surgery is not particularly difficult. Later HH may occur in the context of the MEN-1 syndrome and is then multifocal in nature. In MEN-1 patients, a distal spleen-saving pancreatectomy with enucleation of lesions in the head seems justified. Insulin-producing lesions in non-MEN-1 patients should be enucleated. There should always be a suspicion of malignancy. Also, in older children, surgery for hyperinsulinism should be performed laparoscopically.

Insulin resistance and depressive symptoms in young adult males: findings from Finnish military conscripts

OBJECTIVE

To investigate whether the association between insulin resistance (IR) and depressive symptoms is present already in young adult males. The association between IR and depression has been poorly studied, although the existence of a connection of Type II diabetes with depression is well established. We previously demonstrated at epidemiological level in two groups of men aged 31 years and 61 to 63 years that IR is linked with depressive symptoms.

METHODS

In a cross-sectional study, involving 1054 healthy Finnish male military conscripts of about 19 years of age, IR was defined through homeostasis model assessment (HOMA-IR). The severity of the depressive symptoms was evaluated through a Finnish modification of the 13-item Beck Depression Inventory (R-BDI). Moderate-to-severe depressive symptoms were said to be present, if the R-BDI score was > or = 8, and mild depressive symptoms were present if the R-BDI score was 5 to 7.

RESULTS

After adjusting for confounders, moderate-to-severe depressive symptoms increased the risk for IR, as defined by the highest decile of the HOMA-IR, up to 2.8-fold (odds ratio = 2.8; 1.2-6.5). Mild depressive symptoms were not significantly associated with IR.

CONCLUSIONS

In young adult males, co-occurring strictly defined IR seems to be positively associated with current moderate-to-severe depressive symptoms.

Hyperinsulinemia in pediatric patients with chronic kidney disease: the role of tumor necrosis factor-alpha

We sought to determine the prevalence of hyperinsulinemia and insulin resistance in pediatric patients with chronic kidney disease (CKD) stages 2-4. Data were collected on 43 subjects, aged 6-21 years with mean glomerular filtration rate (GFR) = 47 ml/min per 1.73 m(2) body surface area. Patients were grouped by body mass index (BMI) as either non-lean (>85th percentile) or lean (<or=85th percentile). Fourteen (33%) subjects had hyperinsulinemia, and seven (16%) had elevated homeostasis model assessment of insulin resistance (HOMA-IR). Non-lean subjects had a higher serum insulin level (21.0 microU/ml vs 13.4 microU/ml, P < 0.0001) and HOMA-IR (4.9 vs 3.2, P < 0.001) than lean subjects had. The prevalence of hyperinsulinemia was higher in non-lean patients (40%) than in lean patients (29%) but was not statistically significant. High HOMA-IR was present in six (40%) non-lean subjects and in one lean subject (P < 0.001). Correlation analysis demonstrated that serum insulin level was significantly associated with BMI, leptin and tumor necrosis factor (TNF)-alpha. Stepwise regression determined that increased BMI (P = 0.003) and TNF-alpha (P = 0.01) independently predicted higher insulin level in the whole cohort. Separate analysis for lean subjects showed no significant associations between serum insulin level and BMI; TNF-alpha was the only independent predictor of serum insulin (beta = 1.11, P = 0.01). We conclude that hyperinsulinemia and insulin resistance are frequent in pediatric CKD. In lean patients inflammation appears to be an important determinant of serum insulin level.

Insulin resistance in adolescents

OBJECTIVES

To investigate the relationship of other body mass index (BMI) ranges with Homeostasis Model Assessment-Insulin Resistance (HOMA-IR), a surrogate marker for insulin resistance in adolescents.

STUDY DESIGN

Cross-sectional analysis of a nationally representative sample of 1837 nondiabetic, nonpregnant 12 to 19 year old persons from the National Health and Nutrition Examination Survey, 1999-2002. The main outcome measurement of insulin resistance was calculated as HOMA-IR > 3.16.

RESULTS

Having a BMI > or = 75th percentile is associated with a high HOMA-IR levels. As the BMI percentile increases, the odds of high HOMA-IR levels increase (BMI percentile 75-84.9, OR 4.277, 95% CI 2.090-8.752; BMI percentile 85-94.9, OR 4.299, 95% CI 2.158-8.563; BMI > or = 95th percentile, OR 17.907, 95% CI 11.360-28.228).

CONCLUSION

Adolescents with BMI percentile of 75 to 84.9, which represents approximately 1.2 million US adolescents, have not previously been identified as having higher HOMA-IR levels.

Insulin resistance in children and adolescents

IR is hypothesized to be the important pathophysiologic link between adiposity and future development of type 2 diabetes and cardiovascular disease. A variety of methods for measuring IR have been validated in children, from the gold-standard hyperinsulinemic euglycemic clamp, to simple fasting measures based on fasting insulin and glucose levels. Studies have shown that there are a number of important risk factors for IR in children, including adiposity and visceral adiposity, race/ethnicity, puberty, a family history of type 2 diabetes, sex, and being small for gestational age or prematurity. However, obesity represents the critical risk factor for IR in children. Greater than 50% of obese adolescents in the US have IR. Formal assessment of IR in obese children may represent an important strategy for improving the efficacy of pharmacologic therapy for weight loss and chronic disease prevention.