Relation of fasting insulin to blood pressure and lipids in adolescents and parents

Concordance of haemoglobin A1c, blood pressure and C-reactive protein between children and their parents in Chinese households

BACKGROUND

China has the world's highest diabetes prevalence, which along with hypertension and inflammation continues to grow particularly among children. Little is known about the strength of the association of these cardiometabolic risk factors between parents and their children; thus, the potential of household-based strategies to reduce risk is unknown.

OBJECTIVES

The objective of the study is to examine the parent-child association for haemoglobin A1c (HbA1c), blood pressure (BP) and C-reactive protein (CRP) in a large, geographically diverse Chinese sample.

METHODS

In 940 parent-child pairs (children aged 7-17 years) who participated in the 2009 China Health and Nutrition Survey, we measured each individual's HbA1c and CRP using fasting blood and BP. We used sex-specific random-effects linear regression to examine the parent-child association for these risk factors, accounting for within-family clustering.

RESULTS

Child's HbA1c was positively associated with parental HbA1c. Beta coefficients ranged from 0.06 (95% CI 0.03-0.12) for father-daughter to 0.43 (95% CI 0.28-0.58) for mother-son pairs. We also detected a positive mother-daughter association for BP and positive father-child associations for CRP.

CONCLUSION

The statistically significant parent-child association for HbA1c, BP and CRP in Chinese families suggests that household-based interventions could be useful for confronting the high rates of diabetes, hypertension and inflammation in China.

Pediatric hypertension: An update on a burning problem

A large number of adults worldwide suffer from essential hypertension, and because blood pressures (BPs) tend to remain within the same percentiles throughout life, it has been postulated that hypertensive pressures can be tracked from childhood to adulthood. Thus, children with higher BPs are more likely to become hypertensive adults. These “pre-hypertensive” subjects can be identified by measuring arterial BP at a young age, and compared with age, gender and height-specific references. The majority of studies report that 1 to 5% of children and adolescents are hypertensive, defined as a BP > 95^th percentile, with higher prevalence rates reported for some isolated geographic areas. However, the actual prevalence of hypertension in children and adolescents remains to be fully elucidated. In addition to these young “pre-hypertensive” subjects, there are also children and adolescents with a normal-high BP (90^th-95^th percentile). Early intervention may help prevent the development of essential hypertension as they age. An initial attempt should be made to lower their BP by non-pharmacologic measures, such as weight reduction, aerobic physical exercise, and lowered sodium intake. A pharmacological treatment is usually needed should these measures fail to lower BP. The majority of antihypertensive drugs are not formulated for pediatric patients, and have thus not been investigated in great detail. The purpose of this review is to provide an update concerning juvenile hypertension, and highlight recent developments in epidemiology, diagnostic methods, and relevant therapies.

Association of leptin and insulin with childhood obesity and retinal vessel diameters

OBJECTIVE

Childhood obesity is associated with an impaired retinal microcirculation. The aim of the study was to investigate the association between specific obesity-related biomarkers, physical fitness and retinal vessel diameters in school children.

DESIGN AND SUBJECTS

We studied 381 children aged 10-11 years (body mass index (BMI): 19.3±3.7 kg m(-2)) in a school-based setting.

MEASUREMENTS

Anthropometric measurements and blood sampling were conducted using standard protocols for children. The serum biomarkers leptin, adiponectin, insulin as well as interleukin-6 (IL-6) were analyzed. Physical fitness was determined by a six-item-test battery and physical activity by use of a questionnaire. Central retinal arteriolar equivalent (CRAE), central retinal venular equivalent (CRVE) and the arteriolar-to-venular diameter ratio (AVR) were assessed with a non-mydriatic vessel analyzer (SVA-T) using a computer-based program.

RESULTS

Compared with normal weight children (n=254), obese children (n=39) showed higher leptin (P<0.001), higher insulin (P<0.001), higher IL-6 (P<0.001) and lower adiponectin levels (P=0.013). Obese children demonstrated wider CRVE (P=0.041) and lower AVR (P<0.001). Higher leptin levels were associated with wider CRVE (P=0.032) and lower AVR (P=0.010), that was BMI dependent. Insulin levels were associated with arteriolar (P=0.045) and venular dilatation (P=0.034) after adjustment for BMI. No significant associations between adiponectin levels, IL-6 levels, physical fitness or physical activity and retinal vessel diameter were observed. Lower leptin levels were independently correlated with higher physical fitness (r=-0.33; P<0.001).

CONCLUSION

Leptin and insulin levels are associated with changes of the retinal microcirculation. Especially insulin seems to be a good target marker for the cardiometabolic risk assessment in children since elevated insulin levels are independently associated with microvascular end-organ alterations at an early stage. Lifestyle intervention studies are warranted to examine whether improvement of physical fitness or weight reduction can affect cardiometabolic risk markers and reverse alterations of the retinal microcirculation.

Joint association of physical activity/screen time and diet on CVD risk factors in 10-year-old children

The increasing prevalence of childhood overweight and obesity has been associated with an increased risk for cardiovascular disease (CVD). While several studies examined the effect of single behaviors such as physical activity (PA), sedentary behavior or diet on CVD risk, there is a lack of research on combined associations, specifically in children. Therefore, the purpose of this study was to examine the joint association of PA or screen time (ST) and diet on CVD risk factors in children. PA, STand diet were assessed via questionnaire in 210 fifth grade students (age: 10.6 ± 0.4 years). The healthy eating index (HEI) was subsequently calculated as indicator for diet quality. Height, weight, % body fat, and resting blood pressure were measured according to standard procedures and blood samples obtained via fingerprick were assayed for blood lipids. Total cholesterol HDL ratio (TC:HDL), mean arterial pressure (MAP), and % body fat were used as indicators of CVD risk. 55% of children did not meet current PA recommendations on at least 5 days/week and 70% exceeded current recommendations for ST. Further, only 2.5% possessed a "good" diet (HEI> 80). There was no significant association of PA or STand diet on CVD risk score. Neither TC:HDL, MAP, and % body fat nor the total CVD risk score was significantly correlated with diet, PA, or ST. Children in the high PA group, however, had significantly better diet scores. Despite the fact that self-reported PA, ST, or dietary intake were not directly related to CVD risk in this sample, higher activity levels were associated with a healthier diet and lower ST indicating an overall healthier lifestyle of this subgroup.

Cross-sectional association between blood pressure, in vivo insulin sensitivity and adiponectin in overweight adolescents

AIMS

To examine the cross-sectional relationship between blood pressure (BP) and (1) in vivo insulin sensitivity (IS) and (2) circulating adiponectin levels in overweight adolescents, and to determine if these relationships are driven by adiposity.

METHODS

Sixty-five white pubertal overweight adolescents underwent a hyperinsulinemic-euglycemic clamp to measure IS. Body composition and abdominal adiposity were determined by dual energy X-ray absorptiometry and computed tomography scan. BP was measured by an automated sphygmomanometer every 10 min over 1 h, between 06:00 and 07:00 a.m.

RESULTS

In vivo IS was not associated with BP after adjustment for adiposity measurements (body mass index, percentage body fat or abdominal adiposity). However, adiponectin was inversely related to systolic BP independent of adiposity.

CONCLUSION

Our findings demonstrate that in overweight adolescents the relationship between in vivo IS and systolic BP is mediated through adiposity. However, the association between adiponectin and BP is independent of adiposity suggestive of a potential modulatory role of adiponectin in BP regulation.

Pediatric nonalcoholic fatty liver disease: A clinical and laboratory challenge

The true prevalence of pediatric nonalcoholic fatty liver disease (NAFLD) is unknown. Challenges in determining the population prevalence of NAFLD include the type of test (and the reference intervals used to define normal and abnormal), the type of population (general population, hospital series), the demographic characteristics of the population sampled, and the nature of the study design. The natural history of pediatric NAFLD remains uncertain. The issue of when to perform a liver biopsy in children with suspected NAFLD remains controversial. Children with NAFLD but normal alanine aminotransferase are rarely investigated. However, evidence of alterations in glucose metabolism parameters should prompt a better understanding of the natural history of pediatric NAFLD not only in terms of the progression of liver disease but also regarding its potential relationship with other health outcomes such as type 2 diabetes mellitus and cardiovascular disease. This evidence could make liver biopsy mandatory in the majority of cases at risk of progressive and severe hepatic and extrahepatic disease. This conclusion, however, raises the question of the feasibility of liver biopsy assessment in an extremely large at risk population, and of the cost/effectiveness of this policy. There is a considerable, continuous interest in reliable, noninvasive alternatives that will allow the prognosis of pediatric NAFLD to be followed in large community or population-based studies.

Insulin resistance and metabolic syndrome in the pediatric population

The metabolic syndrome is a constellation of specific anthropometric, physiological, and biochemical abnormalities predisposing affected individuals to the development of diabetes and cardiovascular disease. The syndrome is well described in the adult literature. However, its description in the pediatric literature is more limited. Due in large part to the normal physiological changes that occur in children and adolescents with respect to growth and puberty, investigators have also struggled to establish a standard definition of the syndrome in the pediatric age group, hindering coordinated research efforts. However, whatever definition of the syndrome is used, the prevalence of the metabolic syndrome in the pediatric age group has increased worldwide. Insulin resistance is the principal metabolic abnormality that is common to the development of the metabolic syndrome in both children and adults. This review summarizes current research regarding the pathophysiology of insulin resistance and how this may contribute to specific abnormalities seen in children and adolescents with the metabolic syndrome. Specifically, insulin resistance in pediatric patients is correlated with cardiovascular risk factors such as elevated blood pressure, dyslipidemia, and type 2 diabetes mellitus, all of which are significant risk factors for adult disease. In addition, current treatment and prevention strategies, including lifestyle modifications, pharmacologic agents, and certain surgical therapies, are highlighted. The need for collaborative changes at the family, school, city, state, and national levels to address the growing prevalence of the metabolic syndrome in the pediatric age group is also reviewed.

Obesity without established comorbidities of the metabolic syndrome is associated with a proinflammatory and prothrombotic state, even before the onset of puberty in children

BACKGROUND

Metabolic syndrome (MS)-related comorbidities in obesity, such as hypertension, dyslipidemia, and glucose intolerance, are increasingly recognized in children, predisposing them to early cardiovascular disease.

OBJECTIVE

The objective of the study was to investigate whether markers of inflammation and prothrombosis are abnormal in obese children without established MS comorbidities across puberty, as compared with lean, age-matched controls.

SUBJECTS AND METHODS

Obese children (body mass index >95%) with normal fasting glucose, blood pressure, cholesterol and triglycerides were recruited; lean controls (body mass index 10-75%) had no first-degree relatives with MS. High-sensitivity C-reactive protein (hsCRP), IL-6, plasminogen activator inhibitor 1, and fibrinogen concentrations were measured. Body composition was assessed by waist circumference and dual-energy x-ray absorptiometry.

RESULTS

Of 623 children screened, 203 enrolled (106 males, 97 females), aged 7-18 yr, 115 obese, 88 lean (balanced for age and gender), 99 prepubertal, and 104 pubertal. Many screen failures were due to silent comorbidities. Obese subjects with insulin resistance but without MS comorbidities had about 10 times higher hsCRP concentrations than controls and higher fibrinogen, IL-6, and plasminogen activator inhibitor-1 (P < 0.01 all). Differences were significant, even in the prepubertal cohort. hsCRP and fibrinogen correlated with waist circumference (r = 0.73 and 0.40, respectively) and percent fat mass (r = 0.76 and 0.47) (P < 0.0001).

CONCLUSION

Childhood obesity per se is associated with a proinflammatory and prothrombotic state before other comorbidities of the MS are present and even before the onset of puberty. Whether biomarkers like hsCRP and fibrinogen are useful in assessing cardiovascular risk and whether these abnormalities are reversible with earlier therapeutic interventions in very young obese children requires further study.

Association of BMI and fasting insulin with cardiovascular disease risk factors in seven-year-old Icelandic children

OBJECTIVE

. To look at overweight and common cardiovascular disease (CVD) risk factors, and associations with body mass index (BMI) and fasting insulin in seven-year-old schoolchildren in Reykjavik, Iceland.

STUDY DESIGN

Cross-sectional study of seven-year-old schoolchildren.

SETTING

Six elementary schools in Reykjavik.

SUBJECTS

All children attending second grade in these six schools were invited to participate.

MAIN OUTCOME MEASURES

Overweight, fasting serum insulin, CVD risk factors.

RESULTS

Some 14% of the participating children were classified as overweight. Overweight children had higher fasting insulin, higher fasting glucose, and higher systolic and diastolic blood pressure. Furthermore, they had significantly lower total cholesterol (TC), lower high-density lipoprotein (HDL), and lower low-density lipoprotein (LDL) but a similar TC/LDL ratio to normal-weight children. The factors that were strongly associated with BMI were serum fasting insulin, systolic blood pressure (SBP), HDL and fasting glucose, while the sum of four skinfolds, triglycerides, glucose, and LDL were highly associated with fasting insulin.

CONCLUSION

Overweight children are likelier to have unfavourable levels of common CVD risk factors included in metabolic syndrome, but surprisingly had lower LDL and TC. Skinfold thickness, higher triglyceride and glucose levels, and being female were associated with increased serum insulin.

Non-alcoholic fatty-liver disease in pediatric populations

The increasing prevalence of obesity is not only observed in adults. Children are affected by obesity and related diseases, such as chronic liver disease, more frequently than in the past. Nonalcoholic fatty-liver disease is an important cause of chronic liver disease and in the near future will become important worldwide. Considering this phenomenon, it is important for gastroenterologists and hepatologists to be aware of the presence of nonalcoholic fatty-liver disease in pediatric populations and to treat it adequately. This practice will have important benefits for future generations. This review discusses the most important aspects in epidemiology, diagnostics and treatment of nonalcoholic fatty-liver disease in children.

Update on the metabolic syndrome in children

PURPOSE OF REVIEW

Provides an update on the metabolic syndrome in childhood.

RECENT FINDINGS

The metabolic syndrome is increasingly recognized among children. It is nearly exclusively encountered in overweight and obese individuals and is associated with atherosclerosis. Development and clustering of cardiovascular risk factors is influenced by many characteristics including heritable traits, prenatal and infantile influences, diet, physical activity, and socioeconomic status.

SUMMARY

Epidemiological data have become mature in this area. Efforts to design and implement systems to prevent and treat the metabolic syndrome are required.

Evaluation of glucose intolerance in adolescents relative to adults with type 2 diabetes mellitus

AIM

There is an increasing trend in the prevalence of type 2 diabetes mellitus (DM2) in childhood and adolescence, while positive family history of DM2 and obesity are the most important risk factors. To study the influence of family history and obesity on glucose intolerance in our country was the aim of this study.

STUDY DESIGN AND METHODS

A total of 105 children and adolescents aged 10-18 years (mean 13.3 +/- 2.5 years) were included in the study. All children and adolescents were divided into three groups according to positive family history of DM2 and obesity, and an oral glucose tolerance test (OGTT) was performed for all. Prediabetes was defined as impaired glucose tolerance (IGT) and/or impaired fasting glucose (IFG). Insulin secretion and insulin resistance were estimated using the insulinogenic index; and the homeostatic model assessment for insulin resistance (HOMA-IR) and Matsuda index, respectively.

RESULTS

The prevalence of prediabetes was 15.2% in the whole group, while it was 25.5% in obese children who also had a positive family history of DM2. The frequency of hyperinsulinism was 57.1% in all groups. Prediabetic children had significant insulin resistance (HOMA-IR 11.5 +/- 7.1 and 4.1 +/- 6.4, respectively, p = 0.034).

CONCLUSIONS

Obesity and glucose intolerance are also a problem in developing countries. The risk of prediabetes in children is highest in obese children who also have a positive family history of DM2. There is a need for a lifelong preventive program starting in childhood to avoid DM2 and decrease cardiovascular risk factors

Reduced insulin sensitivity and the presence of cardiovascular risk factors in short prepubertal children born small for gestational age (SGA)

BACKGROUND

Epidemiological studies have shown that the metabolic syndrome, a combination of type 2 diabetes mellitus, hypertension, dyslipidaemia and a high body mass index (BMI), occurs more frequently among adults who were born with a low birth weight. Because insulin is thought to play a key role in the pathogenesis of this syndrome we investigated insulin sensitivity and risk factors for cardiovascular disease in short prepubertal children born small for gestational age (SGA).

PATIENTS AND METHODS

Frequently sampled intravenous glucose tolerance tests (FSIGT) were performed in 28 short prepubertal children born SGA. Short stature was defined as a height < -2SD. SGA was defined as a birth length and/or a birth weight for gestational age < -2SD. Twelve short children born appropriate for gestational age (AGA) were used as controls for the FSIGT's results only. AGA was defined as a birth weight and/or birth length for gestational age > -2SD. In short SGA children, blood pressure (BP), fasting levels of serum free fatty acids (FFA), triglycerides (TG), total cholesterol (TC), high-density lipoprotein (HDL) cholesterol and low-density lipoprotein (LDL) were measured and compared to reference values.

RESULTS

Mean insulin sensitivity (Si) level in short SGA children was significantly reduced to 38% of the mean Si level measured in short AGA controls (P = 0.004). Mean acute insulin response (AIR) was significantly higher in SGA children compared to short AGA controls (P < 0.001). Differences in Si and AIR between the two groups remained significant after adjusting for age and BMI (P < 0.001 and P = 0.003, respectively). The mean (SD) systolic BP SDS was 1.3 (1,1), being significantly higher than zero. Mean fasting serum levels of FFA, TC, TG, HDL and LDL were all within the normal range. However, 6 of the 28 SGA children had serum FFA levels above the normal range. Cardiovascular risk factors could statistically be represented in two clusters. Both clusters played a significant role in the development of insulin insensitivity (1/Si).

CONCLUSION

Although the metabolic syndrome has been described in adulthood, our study showed that risk factors for the development of type 2 diabetes mellitus and cardiovascular disease are already present during childhood in short prepubertal children born SGA, suggesting a pretype 2 diabetes mellitus phenotype.

Obesity, insulin resistance, and other clinicopathological correlates of pediatric nonalcoholic fatty liver disease

OBJECTIVE

To describe the clinical characteristics of nonalcoholic fatty liver disease (NAFLD) in children, including insulin resistance, and to test for correlation with liver pathology.

STUDY DESIGN

A retrospective review of children with biopsy-proven NAFLD at Children's Hospital San Diego from 1999 to 2002. Liver biopsy specimens were independently reviewed by two pathologists.

RESULTS

Children with NAFLD (n=43) were mostly male (70%), Hispanic American (53%) and obese (88%). The criteria for insulin resistance were met by 95% of subjects. Steatosis was predicted by the combination of quantitative insulin sensitivity check index, age, and ethnicity (P<.0001). Portal inflammation was predicted by the combination of ALT and fasting insulin (P=.0009). Perisinusoidal fibrosis was predicted by the combination of AST, fasting insulin, and BMI Z score (P<.0001). Portal fibrosis was predicted by the combination of right upper quadrant pain and homeostasis model assessment of insulin resistance (P=.0028).

CONCLUSIONS

We identified significant predictors of liver pathology in children with NAFLD. Children being evaluated for NAFLD should be screened for insulin resistance, which is nearly universal and correlates with liver histology.

Relation of insulin resistance to blood pressure in childhood

OBJECTIVE

To determine the relation between blood pressure and insulin resistance in children and the differences between fasting insulin and the insulin clamp in that relation.

METHODS

Children were randomly selected after blood pressure screening of 12 043 fifth--eigth grade Minneapolis, Minnesota, students, with stratification by systolic blood pressure (SBP) percentile [half from the upper 25th percentile (high blood pressure) and half from the lower 75th percentile (low blood pressure)]. Euglycemic insulin clamps were performed with an insulin infusion rate of 1 mU/kg per min and a variable infusion of 20% glucose to maintain plasma glucose at 5.6 mmol/l (100 mg/dl). Insulin sensitivity (Mlbm) is defined as the amount of glucose required to maintain euglycemia (mg glucose infused/kg lean body mass (LBM)/min.

RESULTS

Diastolic blood pressure was not significantly correlated with any of the body measurements or laboratory data. SBP was significantly correlated with virtually all measures of body size in males and females. SBP and Mlbm were not significantly correlated in either sex. The correlation between SBP and fasting insulin was significant for boys and girls, but became non-significant after adjustment for BMI. All measures of body fatness were significantly greater in the high blood pressure group, and a significant clustering effect for fasting insulin, BMI, triglycerides, and HDL-C was related to blood pressure. The clustering effect was similar when Mlbm was substituted for fasting insulin and was similar for boys, girls, blacks and whites.

CONCLUSIONS

These results suggest that level of blood pressure in children is mediated through body fat and that insulin resistance, as determined by the insulin clamp, does not play a primary role at this age of development. Nevertheless, the clustering effect of the risk factors according to SBP grouping is consistent with an early relation of blood pressure to the insulin resistance syndrome.

Insulin resistance syndrome in childhood: associations of the euglycemic insulin clamp and fasting insulin with fatness and other risk factors

OBJECTIVE

Our objective was to describe in children the relation of fatness and insulin resistance to the risk factors associated with the insulin resistance syndrome and to compare fasting insulin with the euglycemic insulin clamp as a measure of insulin resistance in children.

STUDY DESIGN

This was a random selection of participants after blood pressure screening of 12,043 students in the fifth through eighth grades. Euglycemic insulin clamp studies with an insulin infusion rate of 1 mU/kg/min and a variable infusion of 20% glucose to maintain euglycemia, that is, plasma glucose at 5.6 mmol/L. Insulin sensitivity (M(lbm)) is defined as the amount of glucose required to maintain euglycemia (milligrams of glucose infused per kilogram lean body mass per minute).

RESULTS

Body mass index was significantly correlated with fasting insulin and significantly inversely correlated with M(lbm). Fasting insulin was significantly correlated with systolic blood pressure in both sexes, all lipids, except high-density lipoprotein-cholesterol in males and triglycerides and high-density lipoprotein-cholesterol in females, but after adjustment was done for body mass index, it was significantly related only to triglycerides. M(lbm) was significantly correlated only with triglycerides and high-density lipoprotein-cholesterol, and this did not change after adjustment was done for body mass index. A clustering effect for the risk factors was seen in children in the lowest quartile of M(lbm) (highest degree of insulin resistance) compared with children in the highest quartile of M(lbm) (lowest degree of insulin resistance).

CONCLUSIONS

As defined by M(lbm), there is an early association of insulin resistance, independent of body fat, with the risk factors. There is a significant relation between fasting insulin, as an estimate of insulin resistance, and the risk factors, but this is significantly influenced by body fatness. The clustering of risk factors according to level of M(lbm) suggests that adult cardiovascular disease is more likely to develop in children with the greatest degree of insulin resistance.

Reduction of cardiovascular disease: what is the role of the pediatrician?

It is apparent from the results of the 1995 and 1998 surveys reported by Kimm et al in this issue of Pediatrics that pediatricians are interested in blood pressure and lipids but uncertain about the management of these coronary heart disease (CHD) risk factors. Data from longitudinal epidemiologic studies initiated in pediatric cohorts support the important role for pediatricians in the detection of children at risk for CHD, and detection should be followed by effective intervention/treatment programs. However, the latter may be difficult in most office practices, because of the intensive effort by specialized personnel required to successfully reduce CHD risk.