Obesity Research & Clinical Practice
Volume 6, Issue 1 , Pages e1-e8, January 2012

Association between insulin resistance, cardiovascular risk factors and overweight in Japanese schoolchildren

  • Chie Fujii

      Affiliations

    • Department of School Health Sciences, Aichi University of Education, 1 Hirosawa, Igaya-cho, Kariya, Aichi 448-8542, Japan
    • Corresponding Author InformationCorresponding author. Tel.: +81 566 26 2499; fax: +81 566 26 2499.
    • ,
  • Hisataka Sakakibara

      Affiliations

    • Department of Public Health and Community Nursing, Nagoya University School of Health Sciences, Aichi, Japan

Received 9 February 2011; received in revised form 8 April 2011; accepted 12 April 2011. published online 19 May 2011.

Article Outline

Summary 

Objective

The aim of this study was to examine the association between insulin resistance, cardiovascular risk factors and overweight in Japanese schoolchildren.

Methods

A cross-sectional study was performed on 310 schoolchildren (155 boys and 155 girls) of the fifth grade and the eighth grade in a town in Nagano Prefecture, Japan. The survey was conducted on anthropometric, blood examinations, and by calculation of body mass index (BMI: body weight/body height2) and HOMA-IR (fasting insulin×fasting glucose/405).

Results

Hemoglobin A1c and fasting glucose were not associated with BMI, whereas fasting insulin and HOMA-IR were significantly higher in overweight children in comparison with the lowest quartile BMI group. In the overweight, the mean and standard deviation of HOMA-IR were 2.51±1.01, and the prevalence of HOMA-IR≧2.5 was 46.8%. Schoolchildren with HOMA-IR≧2.5 had more several cardiovascular risk factors.

Conclusions

Insulin resistance was observed in overweight Japanese children, though their hemoglobin A1c and fasting glucose were within the normal range. In addition, with higher BMI, the number of cardiovascular risk factors was increased. Weight management should be started in childhood.

Keywords: Insulin resistance, Cardiovascular risk factors, Overweight, Schoolchildren

 

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Introduction 

It has been shown that insulin resistance is a key component of metabolic syndrome, and impaired glucose tolerance is a risk factor of cardiovascular diseases. In the USA 15.8% of children between 6 and 11 years and 16.1% of adolescents reportedly have a body mass index (BMI) in the range of overweight [1]. Similar trends have also been observed in many European countries, where 31.8% of school-aged children are overweight and obese. The prevalence of insulin resistance in the pediatric population is also increasing, particularly among obese children and adolescents. A study has reported that type 2 diabetes in youth is frequent in populations of native North Americans [2]. A school health statistics survey by the Ministry of Education, Culture, Sports, Science & Technology in Japan in 2009 showed a trend of obesity among Japanese children, and the prevalence of overweight and obesity were 10.76% in 10-year-old boys and 8.26% in girls, and 9.71% in 13-year-old boys and 8.13% in girls, respectively. It is 1.5–2 times more than their parents generation when they were in the same age range [3].

Meanwhile, from an autopsy study of participants aged 15–19 years, early atherosclerotic changes were reportedly seen in 20% of the abdominal aortas and 10% of the right coronary arteries. These changes were related to cardiovascular risk factors including low serum high-density lipoprotein (HDL) cholesterol, hypertension, obesity, and impaired glucose tolerance [4]. As with the prevalence of pathological change in atherosclerosis among adults, these findings indicate that as the number of cardiovascular risk factors increases, so does the severity of asymptomatic coronary and aortic atherosclerosis in young people [5], [6], [7], [8], [9], [10], [11].

Many studies have been conducted thus far on cardiovascular risk factors and metabolic syndrome in which insulin resistance and obesity are key components for adults [12], however, there are few studies on insulin resistance of healthy children. Therefore, we conducted a cross-sectional survey to assess the current situation of Japanese schoolchildren by measuring insulin resistance-related items such as fasting blood glucose, fasting insulin and cardiovascular risk factors, and to study the association between physical attributes of children and insulin resistance and cardiovascular risk factors.

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Subjects and methods 

Subjects 

The present participants were a total of 313 schoolchildren aged 10 and 13 in the fifth grade (elementary school) and the eighth grade (junior high school) in a town in Nagano Prefecture, Japan, who underwent an annual school health examination in 2009. Almost all the schoolchildren in the fifth and eighth grades in the town participated in the health examination (96.6%). They consisted of 136 fifth-grade schoolchildren (71 boys and 65 girls) and 177 eighth-grade schoolchildren (87 boys and 90 girls). On that occasion, we conducted additional blood examinations in a total of 310 children (155 boys, 70 fifth graders and 85 eighth graders; and 155 girls, 65 fifth graders and 90 eighth graders). Documents explaining this study were distributed to the schoolchildren and their parents with the cooperation of the schools. Then they gave their written consent to participation in this study from among a total of 313 schoolchildren (participation rate 99.0%). This study was conducted according to the guidelines of the Declaration of Helsinki [13].

Biochemical and anthropometric measurements 

Blood examinations were conducted by measurement of hemoglobin A1c, fasting glucose, fasting insulin, triglycerides, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, total cholesterol, uric acid and by calculation of HOMA-IR (calculated from fasting insulin and fasting glucose; fasting insulin×fasting glucose/405). Blood samples were obtained in the morning after overnight fasting from an antecubital vein with the participants seated. These samples were analyzed at the Shimoina Red Cross Hospital in Nagano Prefecture. Collected blood serum samples were centrifuged and analyzed in parallel on the same day. Hemoglobin A1c concentration was measured by the HPLC method (the levels of hemoglobin A1c were expressed using National Glycohemoglobin Standardization Program units [14]), glucose by the electrode method, and insulin by chemiluminescent enzyme immunoassay. Triglycerides, HDL cholesterol, LDL cholesterol and total cholesterol were measured by enzymatic assay that used the cholesterol oxidase, and uric acid by colorimetric method.

Body height, body weight, waist circumference and blood pressure were measured by a school nursing (yogo) teacher and classroom teachers in an annual health examination in 2009. Body mass index (BMI; body weight (kg)/body height (m)2) was calculated from height and weight, and waist/height ratio was calculated from body height and waist circumference.

Statistical analysis 

Statistical analysis was done using SPSS 13.0J for Windows. T-test was used to compare mean values of examination results between boys and girls. In this study, overweight in children was defined as BMI≧74th centile for males and BMI≧76th centile for females, based on national Japanese data: fifth-grade boys: 18.41kg/m2+; eighth-grade boys: 20.65kg/m2+; fifth-grade girls: 18.74kg/m2+; and eighth-grade girls: 21.41kg/m2+ [15]. Five items were selected as cardiovascular risk factors: overweight, hypertension, impaired glucose tolerance, dyslipidemia, and hyperuricemia, considering the definition of pediatric metabolic syndrome in Japan and cardiovascular risk factors (Table 1) [16], [17].

Table 1. Cardiovascular risk factors were overweight, hypertension, impaired glucose tolerance, dyslipidemia and hyperuricemia.
1. OverweightBody mass index (kg/m2)
≧18.41kg/m2 (fifth-grade boys),
≧18.74kg/m2 (fifth-grade girls),
≧20.65kg/m2 (eighth-grade boys),
≧21.41kg/m2 (eighth-grade girls) or
Waist circumference (cm)≧75.0cm (fifth grade),
≧80.0cm (eighth grade) or
Waist/height ratio≧0.5

2. HypertensionSystolic blood pressure (mmHg)≧125mmHg and/or
Diastolic blood pressure (mmHg)≧70mmHg

3. Impaired glucose toleranceHemoglobin A1c (%)≧6.0% or
Fasting glucose (mg/dl)≧100mg/dl

4. DyslipidemiaTriglycerides (mg/dl)≧120mg/dl and/or
High-density lipoprotein cholesterol (mg/dl)<40mg/dl or
Low-density lipoprotein cholesterol (mg/dl)≧120mg/dl

5. HyperuricemiaUric acid (mg/dl)>7.0mg/dl

One-way analysis of variance was conducted by dividing BMI into five categories with overweight and quartiles, and the mean values of examination results were calculated. Dunnett multiple comparison test was used to compare the BMI lowest value group and each category. In addition, the exact probability method was employed to compare cardiovascular risk factors among three groups based on three HOMA-IR levels; more than 2.5 insulin resistance; 1.7–2.4 borderline; and less than 1.6 in normal range [14].

This study was conducted under the approval of the Ethics Committee of Aichi University of Education.

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Results 

The mean value and standard deviation of hemoglobin A1c was 5.52±0.18% in boys and 5.51±0.20% in girls, which showed no significant difference (P=0.475) (Table 2). The mean value of fasting glucose in boys was 94.3±5.8mg/dl, which was significantly higher (P<0.001) than in girls at 91.7±5.8mg/dl. The mean value of fasting insulin in boys was 7.09±3.27μU/ml, whereas that of girls (8.83±3.74μU/ml) was significantly higher (P<0.001). The mean value of HOMA-IR in boys was 1.67±0.81; that of girls (2.01±0.89) was significantly higher (P<0.001). No significant difference in fasting glucose was found between the fifth graders and eighth graders in both boys and girls, while hemoglobin A1c of the fifth graders was significantly higher in both boys and girls. Fasting insulin and HOMA-IR were significantly higher in both eighth-grade boys and girls.

Table 2. Mean examination results among Japanese schoolchildren.
BoysGirlsP valueb
TotalFifth gradeEighth gradeP valueaTotalFifth gradeEighth gradeP valuea
Number of subjects1557085 1556590
Body height (cm)149.2(13.2)137.5(5.9)158.9 (9.0)<0.001148.4(9.6)139.3(5.7)155.0(5.7)<0.0010.537
Body weight (kg)41.5(11.4)33.4(8.1)48.2(9.1)<0.00141.3(9.7)33.0 (5.8)47.2 (7.3)<0.0010.866
Body mass index (kg/m2)18.3(3.1)17.5(3.3)19.0(2.7)0.00318.5(2.9)16.9 (2.2)19.6 (2.8)<0.0010.568
Waist circumference (cm)63.7 (9.3)61.4(9.5)65.6 (8.7)0.00564.3 (8.4)59.6 (6.7)67.7 (7.9)<0.0010.547
Waist/height ratio0.43 (0.06)0.45 (0.06)0.41 (0.05)<0.0010.43 (0.05)0.43 (0.04)0.44 (0.05)0.2260.392
Systolic BP (mmHg)105.3(11.8)102.5(9.6)107.7 (13.0)0.006102.1 (10.5)99.5 (9.6)103.9 (10.8)0.0100.010
Diastolic BP (mmHg)61.9 (9.6)62.7 (8.7)61.3(10.3)0.37462.6 (10.0)61.3(8.3)63.5(11.0)0.1810.544
Hemoglobin A1c (%)5.52(0.18)5.58(0.21)5.48(0.15)0.0015.51 (0.20)5.59 (0.19)5.45(0.18)<0.0010.475
Fasting glucose (mg/dl)94.3 (5.8)94.7 (6.2)94.0 (5.6)0.42991.7 (5.8)91.5(5.8)91.8(5.8)0.720<0.001
Fasting insulin (μU/ml)7.09 (3.27)5.81 (3.63)8.16 (2.49)<0.0018.83 (3.74)6.85 (2.98)10.26 (3.59)<0.001<0.001
HOMA-IRc1.67 (0.81)1.38(0.91)1.91 (0.63)<0.0012.01 (0.89)1.55(0.69)2.34 (0.87)<0.001<0.001
Triglycerides (mg/dl)49.1 (22.4)46.8(22.1)51.0(22.6)0.24859.8 (32.2)58.4 (26.3)60.9 (36.0)0.6290.001
HDL cholesterol (mg/dl)71.2(14.2)73.1 (15.0)69.7 (13.4)0.13669.2(13.2)68.7 (13.1)69.5(13.4)0.6970.188
LDL cholesterol (mg/dl)92.1 (20.4)96.8 (20.3)88.2(19.8)0.00998.7 (21.2)98.9 (21.4)98.6 (21.2)0.9270.005
Total cholesterol (mg/dl)171.3(24.5)178.3(23.8)165.5(23.7)0.001177.3(23.2)177.1 (25.3)177.5(21.7)0.9200.026
Uric acid (mg/dl)5.18(1.32)4.46 (0.94)5.78(1.30)<0.0014.62(1.21)4.30 (0.98)4.85(1.31)0.004<0.001

Standard deviations in parentheses.

aDifference between fifth-graders and eighth-graders.

bOverall difference between boys and girls.

cHOMA-IR=fasting insulin (μU/ml)×fasting glucose (mg/dl)/405.

Triglycerides (P=0.001), LDL cholesterol (P=0.005) and total cholesterol (P=0.026) in girls were significantly higher than in boys while uric acid of boys was higher than in girls (P<0.001). Systolic BP of boys was significantly higher than in girls (P=0.010), but there was no difference between boys and girls in the mean value and standard deviation of body height, body weight, BMI, waist circumference, waist/height ratio, diastolic BP, and HDL cholesterol.

Table 3 shows the mean value and standard deviations of examination results divided into five groups according to BMI overweight and quartiles. As the BMI is higher, the significantly more numerous cardiovascular risk factors, fasting insulin, HOMA-IR, systolic BP, diastolic BP, uric acid, waist circumference, waist/height ratio (trend P<0.001), triglycerides (trend P=0.013) and body height (trend P=0.027) were observed, whereas the HDL cholesterol (trend P=0.001) was significantly decreased. There were no significant associations between BMI and hemoglobin A1c, fasting glucose, LDL cholesterol, total cholesterol and age.

Table 3. Mean examination results among Japanese schoolchildren according to BMI concentration overweight and quartiles.a
TotalQuartile 1Quartile 2Quartile 3Quartile 4OverweightTrend P
Number of subjects3106262626262
Boys1553131313230
Girls1553131313032
Number of risk factorsb0.79(0.91)0.40(0.61)0.44(0.59)0.52(0.67)0.73(0.77)*1.87(0.93)***<0.001
Age (year)11.7(1.5)11.7(1.5)11.7(1.5)11.7(1.5)11.7(1.5)11.7(1.5)0.936
Body height (cm)148.8(11.5)146.4(10.4)148.5(12.0)148.2(11.5)150.4(12.8)150.6(10.4)0.027
Body weight (kg)41.4(10.5)33.6(6.6)37.5(8.1)*39.8(8.3)***43.7(9.5)***52.2(9.6)***<0.001
Body mass index (kg/m2)18.4(3.0)15.5(1.1)16.8(1.1)***17.8(1.2)***19.0(1.3)***22.9(2.6)***<0.001
Waist circumference (cm)64.0(8.8)57.7(4.7)59.7(4.8)61.9(5.7)**65.8(6.9)***75.0(8.9)***<0.001
Waist/height ratio0.43(0.05)0.39(0.03)0.40(0.02)0.42(0.03)**0.44(0.03)***0.50(0.06)***<0.001
Systolic BP (mmHg)103.7(11.3)97.7(9.1)102.2(10.4)103.4(9.9)*107.3(12.7)***107.7(11.1)***<0.001
Diastolic BP (mmHg)62.2(9.8)58.6(8.3)61.4(10.2)62.1(9.1)64.1(9.8)**65.0(10.4)**<0.001
Hemoglobin A1c (%)5.51(0.19)5.52(0.20)5.49(0.17)5.52(0.17)5.51(0.18)5.54(0.22)0.543
Fasting glucose (mg/dl)93.0(5.9)93.2(6.0)92.5(5.7)93.6(5.7)92.3(6.2)93.4(6.1)0.904
Fasting insulin (μU/ml)7.96(3.61)6.89(3.49)6.90(2.88)7.55(3.26)7.66(2.78)10.81(4.06)***<0.001
HOMA-IRc1.84(0.87)1.60(0.81)1.59(0.68)1.75(0.79)1.75(0.67)2.51(1.01)***<0.001
HOMA-IR percentile category [n (%)]
<2.5243(78.4)53(85.5)54(87.1)49(79.0)54(87.1)33(53.2)<0.001
≧2.567(21.6)9(14.5)8(12.9)13(21.0)8(12.9)29(46.8)
Triglycerides (mg/dl)54.5(28.2)49.9(23.1)52.0(26.8)49.8(20.5)61.0(36.3)59.5(30.5)0.013
HDL cholesterol (mg/dl)70.2(13.7)72.8(12.8)73.4(14.8)70.8(13.6)67.4(12.8)66.7(13.5)*0.001
LDL cholesterol (mg/dl)95.4(21.0)94.1(19.8)90.7(22.8)97.2(21.8)97.6(19.1)97.4(21.3)0.114
Total cholesterol (mg/dl)174.3(24.0)174.6(23.8)172.2(25.2)176.2(26.3)174.6(20.0)174.0(24.9)0.895
Uric acid (mg/dl)4.90(1.30)4.64(1.29)4.47(1.18)4.85(1.21)5.07(1.21)5.47(1.38)**<0.001

Standard deviations in parentheses.

aFifth-grade boys: Quartile 1: ≦15.34kg/m2; Quartile 2: 15.35–16.15kg/m2; Quartile 3: 16.16–16.93kg/m2; Quartile 4: 16.94–18.40kg/m2; Overweight: 18.41kg/m2+. Eighth-grade boys: Quartile 1: ≦17.20kg/m2; Quartile 2: 17.21–18.13kg/m2; Quartile 3: 18.14–18.96kg/m2; Quartile 4: 18.97–20.64kg/m2; Overweight: 20.65kg/m2+. Fifth-grade girls: Quartile 1: ≦15.10kg/m2; Quartile 2: 15.11–16.18kg/m2; Quartile 3: 16.19–17.35kg/m2; Quartile 4: 17.36–18.73kg/m2; Overweight: 18.74kg/m2+. Eighth-grade girls: Quartile 1: ≦17.21kg/m2; Quartile 2: 17.22–18.68kg/m2; Quartile 3: 18.69–19.74kg/m2; Quartile 4: 19.75–21.40kg/m2; Overweight: 21.41kg/m2+.

bRisk factors were overweight, hypertension, impaired glucose tolerance, dyslipidemia and hyperuricemia.

cHOMA-IR=fasting insulin (μU/ml)×fasting glucose (mg/dl)/405.

*P<0.05 vs. Quartile 1 (the lowest quartile).

**P<0.01 vs. Quartile 1 (the lowest quartile).

***P<0.001 vs. Quartile 1 (the lowest quartile).

From comparison of the BMI lowest group (Quartile 1) and other BMI groups, the overweight children (the highest group) showed a significant increase in fasting insulin, HOMA-IR and uric acid, while evidencing a significant decrease in HDL cholesterol. In addition, the mean value±standard deviation of HOMA-IR in the overweight group was 2.51±1.01, which showed insulin resistance. HOMA-IR≧2.5 was also 46.8% which was significantly higher, reflecting the tendency to insulin resistance in overweight Japanese schoolchildren.

On the other hand, as shown in Table 4 shows significant positive association with HOMA-IR and cardiovascular risk factors. The group with HOMA-IR≧2.5 had significantly more cardiovascular risk factors compared to the group with HOMA-IR less than 1.6 (lower value).

Table 4. Absolute and percentage numbers of children with from one to ≧three cardiovascular risk factors.
HOMA-IRaRisk factorsbP valueTrend P
TotalNone1 factor2 factors≧3 factors
Total310(100.0)143(46.1)110(35.5)39(12.6)18(5.8)
≦1.6142(100.0)79(55.6)47(33.1)15(10.6)1(0.7)<0.001<0.001
1.7–2.4101(100.0)46(45.5)41(40.6)11(10.9)3(3.0)
2.5≦67(100.0)18(26.9)22(32.8)13(19.4)14(20.9)

aHOMA-IR=fasting insulin (μU/ml)×fasting glucose (mg/dl)/405.

bRisk factors were overweight, hypertension, impaired glucose tolerance, dyslipidemia and hyperuricemia.

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Discussion 

HbA1c, fasting glucose, fasting insulin and HOMA-IR 

This study conducted a survey on physical attributes of Japanese schoolchildren aged 10 and 13 in the fifth grade and the eighth grade, their insulin resistance and cardiovascular risk factors. The mean value and standard deviation of hemoglobin A1c of boys was 5.52±0.18%, against 5.51±0.20% in girls, which did not reflect a significant difference between boys and girls (P=0.475). The mean value of fasting glucose in boys (94.3±5.8mg/dl) was significantly higher (P<0.001) than in girls at 91.7±5.8mg/dl. The same result was obtained from boys in Spain aged 6–8 years who showed a significantly higher mean value of fasting glucose (91.7±9.7mg/dl) than in girls (89.5±12.5mg/dl) (P<0.001) [18]. However, the means±SD of fasting glucose in German boys aged 5–17 years was 77.3±10.0mg/dl, while that in girls was 76.7±8.8mg/dl, which did not show any significant difference (P=0.45) [19]. The means±SD of fasting glucose of boys in Brazil aged 7–10 years was 87.2±5.7mg/dl, in girls it was 86.5±5.2mg/dl, which also failed to reflect a significant difference [20]. This may be due to a difference in measurement methods, however, Japanese schoolchildren may tend to have a higher fasting glucose value compared to children in other countries.

The mean fasting insulin level of Japanese schoolchildren aged 10 and 13 was 7.09±3.27μU/ml in boys and 8.83±3.74μU/ml in girls, a significantly higher level than in boys (P<0.001). The median (25th; 75th percentiles) of fasting insulin of girls in Germany aged 5–17 years was significantly higher 16.5 (13.3; 20.3)mIU/l than in boys 13.7 (11.0; 17.3)mIU/l (P<0.001) [19]. The mean value of fasting insulin in girls in Brazil aged 7–10 years was significantly higher at 17.8±9.9μUI/ml than in boys at 11.9±5.7μUI/ml (P=0.013) [20]. A higher fasting insulin level was commonly observed in girls in all these countries. However, fasting insulin of Japanese children showed a tendency to be lower than in other countries.

The mean value of HOMA-IR of Japanese boys aged 10 and 13 at 1.67±0.81 was significantly lower than in girls (2.01±0.89) (P<0.001). The median (25th; 75th percentiles) of HOMA-IR in German boys aged 5–17 years was 2.64 (1.95; 3.48), against the significantly higher 3.13 (2.47; 3.88) in girls (P<0.001) [19]. The mean value of HOMA-IR in Brazilian girls aged 7–10 years was 3.8±2.3, which was significantly higher than in the 2.6±1.3 boys (P=0.026) [20]. These results demonstrate that girls are less insulin-sensitive than boys, and they may compensate for the decreased sensitivity by increasing their insulin secretion as reported by Hoffman et al. [21]. Therefore, it is presumed that girls tend to show more insulin resistance than boys [22]. More study about insulin resistance of growing schoolchildren is warranted.

Physical attributes (BMI) and insulin resistance and cardiovascular risk factors 

In the present study we defined cardiovascular risk factors based on the definition of pediatric metabolic syndrome in Japan, then investigated five risk factors such as overweight (including overweight by BMI and visceral obesity by waist circumference and waist/height ratio), hypertension, impaired glucose tolerance (judged by hemoglobin A1c, fasting glucose), dyslipidemia (judged by triglycerides, HDL cholesterol and LDL cholesterol), and hyperuricemia.

At first we studied BMI in five groups of overweight and quartiles, and found that the higher BMI group showed a more significant increase in the number of cardiovascular risk factors, fasting insulin, HOMA-IR, systolic BP, diastolic BP, triglycerides and uric acid, whereas HDL cholesterol was significantly decreased. Although hemoglobin A1c and fasting glucose did not show significant associations with BMI, fasting insulin and HOMA-IR had significantly higher values in the overweight group and the BMI highest value group than the BMI lowest value group. In addition, the mean±standard deviation of HOMA-IR in the overweight group was 2.51±1.01, which showed insulin resistance, and the ratio of HOMA-IR≧2.5 was also 46.8%, which was significantly higher than the 13–20% range of other groups. Thus, a tendency to insulin resistance was observed among overweight Japanese children.

It was also reported that the number of metabolic syndrome risk factors was significantly more often observed in obese children [23], [24]. Another report indicated an association with fetal growth and cardiovascular risk factors [25]. However, the standard for pediatric metabolic syndrome differs from one country to another, and there is still no consensus yet in the present situation [26]. Therefore, it is important to report the results of surveys and studies conducted in a unified way, and to work to prevent the onset of cardiovascular diseases in childhood or the fetal stage in the way most appropriate for each country.

Triglycerides, HDL cholesterol, LDL cholesterol and total cholesterol 

Our study has found that more overweight children showed a significantly higher increase in triglycerides (trend P=0.013) and a significant decrease in HDL cholesterol (trend P=0.001), although no significant association of LDL cholesterol and total cholesterol with BMI was found. Lipid metabolism disorders such as high LDL cholesterol and low HDL cholesterol in children are reportedly a predictor of future atherosclerosis [4]. A report on higher HDL cholesterol in children in Spain suggests the possibility of an association with a lower mortality rate of ischemic cardiac disease, compared with other developed countries [27]. Total cholesterol in U.S. children and adolescents aged 4–19 years tend to decrease year by year, indicating that high HDL cholesterol has an association with the low mortality rate of coronary artery disease [28]. More attention should be paid to lipid metabolism disorders since childhood.

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Conclusion remark 

This analysis of schoolchildren showed an association between physical attributes and insulin resistance and cardiovascular risk factors, and revealed a tendency to insulin resistance in overweight children aged 10 and 13, which could be a risk to initiate a change in atherosclerosis.

This cross-sectional survey conducted with a small number of schoolchildren in a rural area of Japan does not cover secondary sex characteristics which must be considered when growing schoolchildren are participants of research. Future longitudinal research is needed to investigate whether insulin resistance in children would cause onset of cardiovascular disease.

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Conflict of interest 

The authors declare no conflict of interest.

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Acknowledgments 

This study was conducted by grants-in-aid for scientific research, Japan Society for the Promotion of Science. We thank the participants and their parents who gave their time to this study.

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PII: S1871-403X(11)00022-6

doi:10.1016/j.orcp.2011.04.002

Obesity Research & Clinical Practice
Volume 6, Issue 1 , Pages e1-e8, January 2012

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