Metabolic Syndrome Risk Factors Among a Sample of Overweight and Obese Mexican Children

Abstract

J Clin Hypertens (Greenwich).

The objective of this study was to estimate the prevalence and correlations of components of the metabolic syndrome (MetS) using the International Diabetes Federation (IDF) pediatric definition in a cross‐sectional study of 215 overweight/obese Mexican children aged 6 to 12. There are no previous studies of this kind in Mexican children. Clinical, anthropometric, and laboratory measurements were performed. The prevalence of MetS using the pediatric IDF criteria was 6.7% (95% confidence interval, 4.0–11.1). A higher proportion of children in the younger age group had waist circumference above the cutoff, while a higher proportion in the older age group had hyperglycemia. Children with MetS had higher percentages of body fat, body mass index, total cholesterol, and low‐density lipoprotein cholesterol. Increased triglycerides, decreased high‐density lipoprotein cholesterol, and waist circumference were most highly associated with MetS. This has significant implications for public health.

Obesity in children is a rapidly expanding disease across the world ¹ , ² ; it is also an emerging public health problem in Mexico, where its prevalence has increased. Data from the Mexican National Nutrition Survey showed that 26.1% of school‐aged children are overweight or obese. ³ Childhood obesity increases the risk of developing cardiovascular disease, diabetes, hypertension, dyslipidemia, sleep apnea, osteoarthritis, cancer, and psychological disturbances, among others, ¹ , ⁴ and can eventually lead to the metabolic syndrome (MetS). Both cross‐sectional and prospective studies in children have linked MetS, or clusters of factors considered to be part of it, to diabetes, ⁵ , ⁶ cardiovascular disease, ⁷ , ⁸ and hepatosteatosis, ⁹ among other complications.

Few studies have estimated the prevalence of MetS in children and adolescents; reports vary greatly among countries, from 4.2% to 18% and among obese children from 19.5% to 59% ¹⁰ , ¹¹ , ¹² , ¹³ , ¹⁴ , ¹⁵ , ¹⁶ not only because of the characteristics of the studied populations, but mainly because of the different definitions that were used. ¹⁰ , ¹¹ , ¹² , ¹⁵ , ¹⁶ , ¹⁷ , ¹⁸ , ¹⁹ , ²⁰ , ²¹ , ²² Until recently, no standard definition of MetS was available for use in pediatric populations. Consequently, researchers have used an assortment of definitions. In 2007, the International Diabetes Federation (IDF) presented a definition for use in children and adolescents, ¹⁴ however, to this date, we have found only one study using this definition to address the syndrome’s prevalence. ¹³

In Mexico, very few studies have addressed the issue of the prevalence of MetS, each used different clusters of criteria and cutoff values and they reported a prevalence that ranged from 4.8% to 26.1%. ¹² , ²¹ , ²² There are no studies from Mexico using the pediatric IDF definition.

From a clinical and public health perspective, the recognition of MetS in overweight and obese children who have not yet developed a metabolic and/or cardiovascular disease is of great importance. This is especially important for children aged 6 to 9, since the IDF consensus does not include this age group, nor is there any standard definition for them, but they do have a high prevalence of overweight and obesity. Thus, we conducted this study to estimate the prevalence of MetS in children aged 6 to 12 with the pediatric IDF definition. The use of a single unified definition will make it possible to estimate the global pediatric prevalence of MetS, making valid comparisons between countries and addressing strategies for adequate interventions.

Materials and Methods

Study Population

We studied a cross‐sectional sample of 215 overweight and obese school‐aged children from 8 urban and suburban public schools distributed in the metropolitan area of the city of Monterrey, in northern Mexico. Forty‐four children from the same schools with normal range body mass index (BMI) (below the 85th percentile for age and gender) were studied as controls. Participants were ethnically homogeneous (all of them were Mexican‐Hispanic). Inclusion criteria were as follows: attendance at one of the participant schools from the first to the sixth grade; age 6 to 12; BMI ≥85th percentile for age and sex; 12‐hour overnight fast; and signed informed consent from both parents/caretakers and children. The use of drugs for high blood pressure, hyperglycemia, or dyslipidemia was considered an exclusion criterion. Approvals by the Ethics and the Research Committees of the School of Medicine Tecnológico de Monterrey and by the State Education Authorities were obtained, as well as written informed consent from parents and children. In accordance with the IDF criteria for MetS, participants were divided into 2 age groups: (1) children aged 6 to 9 and (2) children aged 10 to 12.

Clinical Evaluation

Parents responded to a questionnaire that asked about familial risk factors: diabetes, myocardial infarction, cerebrovascular event, hypertension, and dyslipidemia. Anthropometric assessment was performed in all participants (n=259) within each school. We measured height, weight, waist circumference (WC), and percentage of body fat (% BF) by bioimpedance, according to standardized methods. BMI was calculated as weight (kg) divided by the square of height (m). Each anthropometric measure was performed by the same trained examiner in all children to control for interobserver variability.

Blood pressure was measured in every participant by the same physician, using an aneroid sphygmomanometer (Welch Allyn, Skaneateles, NY) with an appropriate cuff according to the participant’s size and following the standardized technique described by the American Heart Association; 2 measurements were obtained while the participants were calm and seated, and the average was calculated. Tanner stage was self‐evaluated by means of schematic drawings from which the children selected the most appropriate image.

Laboratory Assessment

Blood samples were obtained after a 12‐hour overnight fast. Samples were kept at 2 to 8°C, centrifuged within the first 3 hours and then refrigerated again at 2 to 8°C. Serum total cholesterol (TC), high‐density lipoprotein cholesterol (HDL‐C), low‐density lipoprotein cholesterol (LDL‐C), triglycerides (TG), and glucose were measured by the technique of reflective photometry (Beer‐Lambert’s law) using an automated analyzer (Architect c8000; Abbott Laboratories, Abbott Park, IL), with an intra‐ and inter‐assay coefficient of variation below 4.7%.

Definitions

To define MetS, we used the pediatric criteria established by the IDF in 2007. ¹⁴ The IDF establishes the diagnosis of the syndrome by the presence of central obesity defined by WC ≥90th percentile for age and gender and at least 2 of the other 4 parameters (Table I).

Table I.

 The International Diabetes Federation Definition of the Metabolic Syndrome in Children and Adolescents

Parameter	Cutoff
Waist circumference	≥90th percentile for age and sex
At least 2 of the following:
SBP, mm Hg	≥130
DBP, mm Hg	≥85
Fasting glucose, mg/dL	≥100
HDL‐C, mg/dL	<40
Triglycerides, mg/dL	≥150

Abbreviations: DBP, diastolic blood pressure; HDL‐C, high‐density lipoprotein cholesterol; SBP, systolic blood pressure.

LDL‐C and TC were classified as altered when equal to or greater than 160 and 200 mg/dL, respectively, according to the reference values for age and gender.

Statistical Analysis

Data are presented either as an absolute number with its respective percentage, or else as means with their 95% confidence intervals (CI). Distributions of continuous variables were examined for skewness and kurtosis and by means of the Kolmogorov–Smirnov test to determine normality of data; nonparametric tests were used when appropriate.

Differences in proportions were evaluated by chi‐squared test and differences in means by Student's t or Mann–Whitney U test, according to the characteristics of the distribution (normal or non‐normal, respectively). Multivariate analysis was performed by means of a binary logistic regression model in which a dichotomous variable of having or not having MetS was used as the dependent variable and WC percentile was introduced to the model (as a categorical dichotomous variable defined by the 90th percentile cutoff) as a predictor and it was adjusted for age and gender. An α value of 0.05 was considered for statistical significance in all cases. All analyses were performed with the use of SPSS 13.0 for Windows (SPSS Inc, Tokyo, Japan).

Results

Anthropometric and Metabolic Characteristics

Blood samples were obtained from 194 children out of the total sample (215 participants) and 44 controls. Subset analysis was performed by gender; boys had significantly higher mean weight (48.71 vs 46.22 kg, P=.020), WC (83.53 vs 80.19 cm, P=.011), systolic blood pressure (SBP) (108.5 vs 105.9 mm Hg, P=.022) and glucose (86.3 vs 83.5 mg/dL, P=.008), whereas girls had higher % BF (33.8 vs 32.5, P=.027); the rest of the measured clinical and laboratory parameters did not differ between genders. Table II presents the anthropometric and laboratory data of the studied participants, categorized by whether or not they met criteria for MetS. Age, gender, and pubertal development were equally distributed between the groups. Participants with MetS had significantly higher % BF, BMI, TC, and LDL‐C than their counterparts (Table II).

Table II.

 Anthropometric and Laboratory Characteristics of Participants With and Without MetS Among Mexican School Aged Children Aged 6 to 12 Years

Characteristic	MetS (+) n=13	MetS (−) n=181	P Value
Sex, No. (%)
Male	6 (46.2)	87 (48.1)	1.0
Female	7 (53.8)	94 (51.9)
Tanner, No. (%)
Prepubertal	9 (69.2)	112 (61.9)	.77
Pubertala	4 (30.8)	69 (38.1)
Age, y	8.6 (7.7–9.6)	9.3 (9.1–9.6)	.165
Weight, kg	59.8 (46.4–73.2)	46.9 (45.3–48.6)	.060
Height, cm	142.0 (135.4–148.6)	139.7 (138.2–141.1)	.418
% BF	45.2 (39.7–50.7)	32.8 (31.7–33.9)	<.001
WC, cm	92.6 (84.2–101.0)	81.5 (80.0–82.9)	<.001
BMI, kg/m 2	28.8 (25.3–32.4)	23.8 (23.3–24.3)	<.001
SBP, mm Hg	112.4 (105.2–119.6)	107.1 (105.6–108.3)	.141
DBP, mm Hg	61.2 (55.4–67.0)	59.3 (58.3–60.4)	.858
Fasting glucose, mg/dL	87.8 (78.8–96.8)	84.6 (83.4–85.9)	.467
Total cholesterol, mg/dL	195.5 (182.3–208.8)	158.0 (153.4–162.6)	<.001
LDL‐C, mg/dL	128.5 (116.5–140.6)	105.8 (101.8–109.9)	.002
HDL‐C, mg/dL	39.9 (36.0–43.8)	38.9 (37.8–40.0)	.384
Triglycerides, mg/dL	224.6 (160.8–288.5)	123.1 (114.7–131.5)	<.001

Data represent mean (95% confidence interval) unless otherwise specified. P value for means was obtained from Student t test or Mann–Whitney U test, as appropriate, and from chi‐squared test in the case of proportions. ^aPrepubertal was considered as Tanner stage I and pubertal as Tanner II through IV. Abbreviations: % BF, percentage of body fat; BMI, body mass index; DBP, diastolic blood pressure; HDL‐C, high‐density lipoprotein cholesterol; LDL‐C, low‐density lipoprotein cholesterol; MetS, metabolic syndrome; SBP, systolic blood pressure; WC, waist circumference.

Hereditary Risk Factors

The presence of the following familiar risk factors was investigated, both in first and second degree relatives: diabetes, myocardial infarction, cerebrovascular event, hypertension, and dyslipidemia. The proportion of participants with the presence of each of the hereditary risk factors was the following: diabetes, 59.1% (95% CI, 52.1–65.7); hypertension, 53.5% (95% CI, 46.6–60.4); dyslipidemia, 37.4% (95% CI, 30.9–44.3); myocardial infarction, 18.2% (95% CI, 13.4–24.1); and cerebrovascular event, 7.6% (95% CI, 4.6–12.2). There was no difference (P=.54) in the presence of familiar risk factors, as participants with MetS had a mean of 1.6 (95% CI, 0.7–2.5) and participants without the syndrome had a mean of 1.8 risk factors (95% CI, 1.6–2.0). No difference was found either in the proportion of participants with each number of risk factors (0–5) between children with and without MetS (P=.458).

MetS and Its Risk Factors

Using the IDF definition for MetS, the prevalence of the syndrome in the total sample was 6.7% (95% CI, 4.0–11.1). None of the normal BMI participants met the criteria for MetS. Prevalence was higher in the 6 to 9 year‐old group, 7.3% (95% CI, 3.8–13.8) than in the 10 to 12 year‐old group, 5.9% (95% CI, 2.5–13.0); this difference was not statistically significant, however (P=.91).

If we use the same parameters and cutoff values proposed by the IDF but defining the syndrome by the presence of any 3 of the 5 criteria, as previous definitions did, ¹⁰ , ¹¹ , ¹² , ¹⁵ , ¹⁶ , ¹⁷ , ¹⁸ , ¹⁹ , ²⁰ , ²¹ , ²² the overall prevalence of MetS in the sample would be 16.5% (95% CI, 11.9–22.4). In the 6 to 9 year‐old group, the prevalence would be 17.4% (95% CI, 11.5–25.6), and for the 10 to 12 year‐old group, the prevalence would be 15.3% (95% CI, 9.2–24.4), with no significant difference between the groups (P=.839). Table III shows the proportion of participants who had each of the parameters altered (according to the IDF criteria), stratified by age groups. A significantly higher proportion of children in the younger age group had WC above the cutoff compared to their older counterparts; in contrast, a significantly higher proportion of children in the older age group had fasting hyperglycemia (Table III).

Table III.

 Proportion of Participants From the Total Sample With Altered Anthropometric and Laboratory Parameters, Stratified by Age Groups

	Prevalence of Altered Clinical and Laboratory Parameters a		P Value
	6–9 y (n=119)	10–12 y (n=96)
WC ≥p90	65 (54.6)	27 (28.1)	<.001
SBP ≥130 mm Hg	1 (0.8)	1 (1)	.574
HDL‐C <40 mg/dL	52 (47.7)	39 (45.9)	.914
Triglycerides ≥150 mg/dL	34 (31.2)	24 (28.2)	.773
Total cholesterol ≥200 mg/dL	15 (13.8)	9 (10.6)	.655
Fasting blood glucose ≥100 mg/dL	2 (1.8)	8 (9.4)	.041
LDL‐C ≥160 mg/dL	6 (5.5)	1 (1.2)	.224

Data represent absolute number (percentage) of participants in each age group with the respective clinical or laboratory variable being abnormal. ^a109 blood samples were obtained and analyzed from the 6 to 9 year‐old participants, and 85 samples from the 10 to 12 year‐old participants. Abbreviations: HDL‐C, high‐density lipoprotein cholesterol; LDL‐C, low‐density lipoprotein cholesterol; p90, 90th percentile for age and sex; SBP, systolic blood pressure; WC, waist circumference.

According to the pediatric IDF definition (see Table I), in the 6 to 9 year‐old group, 23.9% had 1 and 32.1% had 2 of the 5 criteria for MetS; in the group of 10 years and older, 29.4% met 1 and 22.4% met 2 of the criteria. Elevated TG, low HDL‐C and increased WC were the variables that were found to be most abnormal in our sample, both in the MetS population and those without MetS (Table IV).

Table IV.

 Percentage of Participants With Cardiovascular Disease Risk Factor Values Above the Cutoff for Defining MetS (International Diabetes Federation Pediatric Definition)

Cardiovascular Disease Risk Factors	Participants With MetS (n=13)	Participants Without MetS (n=181)	P Value
Triglycerides ≥150 mg/dL	13 (100)	45 (24.9)	<.001
HDL‐C ≤40 mg/dL	9 (69.2)	82 (45.3)	.167
Fasting blood glucose ≥100 mg/dL	4 (30.8)	6 (3.3)	<.001
WC ≥p90	13 (100)	74 (40.9)	<.001
SBP ≥130 mm Hg	2 (15.4)	0 (0)	<.001
DBP ≥85 mm Hg	0 (0)	0 (0)	–

Data represent absolute number (percentage) of participants in each age group with the respective clinical or laboratory variable being abnormal. P value for proportions from chi‐squared test. Abbreviations: DBP, diastolic blood pressure; HDL‐C, high‐density lipoprotein cholesterol; MetS, metabolic syndrome; p90, 90th percentile for age and sex; SBP, systolic blood pressure; WC, waist circumference.

Both the TG cutoff and the blood pressure cutoff in the IDF definition differ greatly from the previous National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) definition for adolescents. ¹⁰ Using this latter definition, the percentage of participants in our sample with altered TG (≥110 mg/dL) would be 53.6% (95% CI, 46.6–60.5), as opposed to 29.9% by the IDF criterion. Regarding blood pressure, NCEP proposed using the 90th percentile for age and gender as cutoff for SBP and diastolic blood pressure. Defined this way, 14.4% (95% CI, 10.4–19.7) of our participants had an elevated SBP and 2.8% (95% CI, 1.3–6.0) had an elevated diastolic blood pressure (vs 1% and 0%, respectively).

A binary logistic regression was performed to study the ability of the 90th percentile of WC, adjusted for age and gender, as a cutoff to predict MetS—if the latter is defined by the presence of any 3 of the 5 criteria. Having a WC below the cutoff was significantly associated with not having MetS (adjusted odds ratio, 0.017; 95% CI, 0.002–0.125; P<.001).

Discussion

As childhood overweight increases, its medical complications are becoming more common and more frequently recognized. ¹ , ⁴ Already, one quarter of the world’s adult population has MetS ²³ and this condition is appearing with increasing frequency in children and adolescents, driven by the growing obesity epidemic in this young population. ¹⁰ , ¹¹ , ¹⁸ Many obese children have one or more features of MetS, ²⁴ with hypertension and hyperinsulinism, dependent on the severity of obesity. ²⁵ , ²⁶ Obese children have a 2‐ to 4‐fold higher risk for hypertension ²⁷ and an approximately 4‐fold higher risk of hyperlipidemia ²⁸ and type 2 diabetes. ² , ²⁹ In Mexico, diabetes mellitus is the second leading cause of general mortality, after cardiovascular disease. ³⁰

As described, the reported prevalence data on MetS in the young have varied markedly, in large part because of disagreement among the variously proposed definitions. Therefore, a simple, easy‐to‐apply clinical definition was proposed by the IDF (Table I). ¹⁴ The new IDF pediatric definition is ranked according to age groups 6 to <10, 10 to <16, and ≥16 years. This was believed to be necessary because of the developmental challenges presented by age‐related differences in children and adolescents. Children <6 years were excluded as a result of insufficient data in this age group. The IDF suggests that below 10 years, MetS should not be diagnosed but a strong message for weight reduction should be delivered to parents and caregivers of those with abdominal obesity.

Numerous studies have established that child and adolescent obesity tracks into adulthood and also predicts MetS in adults, which tends to progress clinically. ⁴ , ⁵ , ⁶ , ⁷ , ⁸ , ¹¹ , ²⁹ Childhood LDL‐C, SBP and BMI are all significantly associated with adult intimal–medial thickness, ³¹ while BMI and adiposity are associated with insulin resistance and type 2 diabetes in children. ³² , ³³ For these reasons, and the lack of consistency in the cutoffs used for children in general and lack of a consensus for children <10 years, we decided to apply the IDF definition for children in our 6 to 9 year‐old group, in the light that the cutoff values (except for WC) are those of adult levels in the IDF adult definition.

We used the new IDF pediatric definition for MetS for 215 overweight and obese Mexican children divided in 2 age categories, 6 to 9 years and 10 to 12 years. Our results showed that the overall prevalence of MetS in the sample was 6.7%; it was 7.3% in the 6 to 9 year‐old group and 5.9% in the 10 to 12 year‐old group, with no significant difference between the groups. The prevalence of MetS in our cohort was lower compared to the 23% to 26% reported by others in obese children, ¹⁰ , ¹¹ , ¹² , ¹⁸ , ¹⁹ using different definitions. Also using the new IDF definition for children,¹⁴ Ford and colleagues¹³ estimated a prevalence of ≈4.5%, which is similar to ours and it is located at the low end of the range of previous estimates (4.2% to ≈50%) from pediatric studies conducted in the United States. ¹⁰ , ¹¹ , ¹⁶ , ¹⁷ , ¹⁸ , ³⁴

Our results might be explained because the IDF retained the adult cutoff values of its adult definition, and previous studies used mostly those parameters adapted for age and sex. We have to consider that the use of adult cutoff values for children possibly underestimates the prevalence of MetS and raises the risk level for cardiovascular and metabolic disease among those identified as having MetS. It has to be taken into account that for Hispanic adults, the WC cutoffs are lower than for other ethnic groups (>80 cm in adult women and >90 cm in men), ³ similarly, it is likely that the same happens for Hispanic children, so we may be underestimating the prevalence of MetS considering we did not calculate WC percentiles based on ethnic‐specific data because there are none for Mexican children.

The IDF selected WC as a sine qua non for MetS because it has been shown that WC is an independent predictor of insulin resistance, lipid levels, and blood pressure, and to correlate more strongly with visceral adipose tissue than BMI (in adults). ³⁵ , ³⁶ , ³⁷ However, previous definitions, even though they included WC as a criterion, did not use it as a prerequisite. Examples include the definition of the NCEP‐ATP III for adults ³⁸ and modified for adolescents by Cook and colleagues, ¹⁰ as well as the pediatric definitions proposed by De Ferranti and associates, ¹⁷ Weiss and associates, ¹¹ and Ford and associates. ³⁹

It has been argued that WC is not very reliable for comparison because of lack of a standardized measurement: it has been measured at the level of the umbilicus, halfway between the iliac crest and the lowest rib, just above the iliac crest, just below the lowest rib and at the narrowest, ⁴⁰ and because it is affected by pubertal development and ethnicity. In our case, we don’t have ethnic specific WC percentile data, and for Mexicans, the WC cutoff for adults is less than that for other populations. All these reasons support our idea that using the IDF definition may be underestimating the MetS prevalence in our population, and thus our need to explore the prevalence of MetS in our population without using WC as a prerequisite.

The fact that a similar estimate of the prevalence of MetS was found in both age groups has important implications from a public health view, since it means that children from the younger age group might be at a higher risk of developing complications, since MetS increases the risk of developing adverse events later in life and tends to progress over time. ⁵ , ⁷

Comparing both age groups and considering each component of MetS, a significantly higher proportion of children in the younger age group had WC above the cutoff value compared to their older counterparts (54.6% vs 28.1%); in contrast, a higher proportion of children in the older age group had fasting hyperglycemia (9.2% vs 1.8%). Since the prevalence of type 2 diabetes has risen dramatically among adolescents in the past 20 years, ²⁹ this older age group of overweight and obese children with hyperglycemia might be a reflection of this emerging trend toward a young onset of type 2 diabetes. Although there was a high prevalence of low HDL‐C among both groups (45.9% vs 47.7%), there was no significant difference between them, as was also the case for hypertension and hypertriglyceridemia.

The age of adiposity rebound refers to the age after infancy at it which the individual’s BMI is lowest and after which it starts to rise to adult levels. The cumulative incidence of type 2 diabetes was 4.7 times higher in a group whose adiposity rebound occurred before 5 years compared with those in whom it occurred after 7 years. ⁴¹ It is likely that the 6 to 9 year‐old group of obese children had their adiposity rebound at a very young age, with the already mentioned implications for the risk of development of type 2 diabetes.

There was no difference in the number of family risk factors between children with MetS and those without it, nor in the proportion of participants with each number of risk factors. Diabetes mellitus was the most common hereditary risk factor (59.1% of the participants), followed by hypertension (53.3%), dyslipidemia (37.4%), myocardial infarction (18.2%) and finally, cerebrovascular accident (7.6%). These results might be largely influenced by the specific genetic background of our population, since it has been shown that Hispanic individuals, when compared to Caucasian or African‐American participants appear to have greater proportion of visceral fat and a higher prevalence of impaired glucose tolerance and type 2 diabetes. ¹⁰ , ¹¹ , ¹⁸ As well, recent evidence shows that Hispanics have a greater risk of developing type 2 diabetes and insulin resistance when compared to other ethnic groups. ¹⁸ , ³⁴ These findings highlight the importance of further ethnically directed research that deepens our insight in this area.

We found 3 variables most commonly associated with MetS. Children with MetS had a significantly higher prevalence of hypertriglyceridemia (100% vs 25%), WC above the 90th percentile (92% vs 41%) and impaired fasting glucose (31% vs 3%) compared to those without the syndrome. Participants with MetS had significantly higher BMI, % BF, TG, TC, and LDL‐C than their counterparts without the syndrome.

Our findings highlight a very similar prevalence of MetS between children younger and older than 10 years, we also found a high proportion of children that even though they do not meet criteria, already have 1 or 2 altered parameters and thus may already bear a heightened risk for premature cardiovascular disease and type 2 diabetes. If the diagnosis of the syndrome is defined by any 3 of the 5 criteria, without WC being an obligated criteria, then the prevalence of MetS more than doubles. Thus, this highlights the IDF recommendation to foster awareness in parents and promote weight loss in children at risk. Adhering to the IDF definition for MetS in children, the results of this study might reinforce the urgency to use a single definition both above and below 10 years and to establish age‐appropriate cutoff values for the rest of the clinical and laboratory parameters besides WC. The earlier the identification of this cluster of metabolic derangements, the better our potential to prevent cardiovascular and metabolic risk factors and their complications tracking all the way through adult life.

Obesity and MetS in children are serious and multifaceted conditions that need our urgent attention. The relationship between obesity and MetS components has been documented in children. Our findings draw attention to a high percentage of overweight and obese young children who may bear a heightened risk for future MetS in adulthood with subsequent increased risks for premature cardiovascular disease and type 2 diabetes, the 2 major causes of death among Mexicans. For these reasons, the recognition of MetS in obese children is of great importance from a clinical and public health perspective.

These findings, however, must be interpreted in light of acknowledged limitations. The study was cross‐sectional and, therefore, causality cannot be inferred. The study sample was comprised only of overweight and obese children, and normal weight children were only included as a reference group. We did not measure insulin levels to correlate with components of MetS. The studied population represents an ethnic group with a high predisposition to hyperglycemia and type 2 diabetes, so generalization to other ethnic groups might be limited.

The observed similar prevalence of MetS in both the 6 to 9 year‐old and the 10 to 12 year‐old groups in these obese Mexican children highlights the need for effective strategies to halt the progression of the syndrome, aimed at preventing weight gain and screening for clinical abnormalities, especially hyperglycemia and type 2 diabetes because of the increased predisposition that Hispanics bear for this entity. Larger population studies are needed to assess the prevalence of MetS in Mexican children, using one standard definition. This is particularly important for children <10 years, for whom no definition has yet been proposed. More studies in children <10 years using the IDF definition and comparing different cutoffs should be conducted in order to value the use of this definition for this age group and provide a standard to facilitate comparisons of study results.

Acknowledgements and disclosures:  Drs Elizondo‐Montemayor and Borbolla‐Escoboza conceived the study, obtained funding, developed the field methodology, and provided guidance and supervision throughout. Dr Elizondo‐Montemayor wrote the manuscript and Dr Borbolla‐Escoboza revised it. Dr Serrano‐González participated in the logistics and field work, compiled the data in the database, assisted with writing the manuscript, and performed the analysis of data and presentation of results. Dr Ugalde‐Casas was responsible for coordinating the logistic process, provided supervision during the field work, and assisted with writing the manuscript. Dr Cuello‐García supervised the statistical analysis and provided significant consultation. All authors read and approved the final version of the manuscript. The authors thank deeply Chantal Treviño, Mariana Treviño, Elena Ortíz, Andrea de la Garza, and Areli Hernández for their invaluable collaboration during the field work, as well as Marisa Zertuche, Luisa Martínez, Claudia Sánchez, Cynthia Ramírez, and Roxana Márquez for their collaboration in constructing the database. The authors thank the State Education Authorities and the State Health Authorities as well as the participant schools for their logistic support. The project was funded by the Health Sciences Division and by the Hematology and Cancer endowed chair of the Instituto Tecnológico y de Estudios Superiores de Monterrey. The authors have no relationships to disclose.