Prevalence of metabolic syndrome in obese Turkish children and adolescents

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Abstract

Objective

The aim of our study was to assess the prevalence of metabolic syndrome and the other metabolic features in obese children.

Methods

We have studied 169 obese children and adolescents (body mass index > 95th percentile), 100 prepubertal and 69 pubertal, aged between 7 and 18 years. Each subject was submitted to an oral glucose tolerance test. The diagnosis of impaired glucose tolerance, type 2 diabetes and metabolic syndrome were defined according to modified WHO criteria adapted for children.

Results

Metabolic syndrome was found in 27.2%, with a significantly higher rate among adolescents aged 12–18 years (37.6%) than among children aged 7–11 years (20%) (p < 0.001). There were no significant differences in the prevalence of metabolic syndrome by sex. The prevalences of insulin resistance, glucose intolerance and type 2 diabetes were 29, 19 and 2% among prepubertal children and 56.5, 27.5 and 4.3% among pubertal group, respectively. The prevalence of fasting hyperinsulinemia in pubertal group was significantly higher than prepubertal children (p < 0.001). Hyperinsulinemia was also more frequent in pubertal children with significant difference (20% versus 43.7%, p < 0.001). Hypertension was significantly more common in adolescents (31.8%) than children (15%) with obesity, as expected (p < 0.013). Overall, dyslipidaemia in prepubertal and pubertal groups was identified in 42 and 55%, respectively, with no significant differences (p = 0.085).

Conclusions

Type 2 diabetes mellitus and metabolic syndrome prevalences among adolescents are quite high in the urban area of Konya, central Anatolia, with abnormal lipid profiles, obesity and nutritional mistakes.

Introduction

Obesity is associated with dyslipidaemia, impaired glucose tolerance (IGT) and insulin resistance, which, in turn, are risk factors for the development of the metabolic syndrome, type 2 diabetes mellitus and cardiovascular disease [1]. It is well known that obesity, especially visceral abdominal fat, increases the risk of developing IGT and type 2 diabetes. More recently, abnormal glucose tolerance has also emerged as a major concern in obese children and adolescents [2]. In several studies, a close relationship between glucose intolerance and type 2 diabetes mellitus was reported and claimed that the risk of developing diabetes was two to eight times more common in cases with IGT compared with normal persons during the following 2–10 years [3], [4], [5].

Environmental factors, including health-related behaviors or lifestyle changes and economic disadvantage, contribute to some of the race or ethnic disparities in the prevalence of the diseases associated with obesity. In year 2000, the first cases of type 2 diabetes were reported in English children [6], reflecting a trend seen in North America over the last 20 years. Affected children are usually overweight or obese, often female, pubertal, predominantly of ethnic minority origin and have a family history of type 2 diabetes [7]. Among Japanese school children, type 2 diabetes is seven times more common than type 1, and its incidence has increased more than 30-fold over the past 20 years, concomitant with changing food patterns and increasing obesity rates [8], [9]. Recently, studies indicate that between 8 and 45% of all new diagnoses of diabetes mellitus in children are type 2 diabetes [10]. The incidence increases with age and obesity.

There are also racial differences in the prevalence of obesity as well as racial differences in the prevalence of health complications associated with obesity [11]. Moreover, the prevalence of obesity and type 2 diabetes in childhood is rising in other developed and affluent countries and is now spreading to less affluent countries. Documented by Cinaz et al. the prevalence of obesity in Turkey among 12,600 children aged 6–14 years was 13.8% [12]. In other Turkish studies, the prevalence of childhood obesity was reported as 9.1 and 12.8% [13], [14].

Therefore, we investigated the prevalences of IGT, insulin resistance, type 2 diabetes and metabolic syndrome in a large cohort of obese Turkish children and adolescents.

Section snippets

Subjects and methods

One hundred and sixty-nine children (93 females and 76 males, aged 10.8 ± 3.0 years), arriving at the outpatient clinic of the Department of Pediatric Endocrinology and Diabetes at Selcuk University Research Center in Konya, Turkey, with the complaint of obesity, were included into our criteria. The children were required to meet the following inclusion criteria: (1) age, 7–18 years; (2) BMI, greater than the 95th percentile for age and gender based on the standards of the Centers for Disease

Abnormal glucose homoeostasis

Criteria were defined according to modified WHO criteria adapted for children [15]. The corresponding categories, when the OGTT is used, are the followings: 2-h post-load glucose (2 h.PG) < 140 mg/dL (<7.8 mmol/L) = normal glucose tolerance; 2 h.PG  140 mg/dL (≥7.8 mmol/L) and <200 mg/dL (<11.1 mmol/L) = impaired glucose tolerance (IGT); 2 h.PG  200 mg/dL (≥11.1 mmol/L) = diagnosis of diabetes. Following American Diabetes Association recommendations, a fasting glucose ≥110 mg/dL (≥6.1 mmol/L) defined impaired fasting

Statistical analysis

Data were expressed as mean ± S.D. IGT, insulin resistance, type 2 diabetes mellitus and metabolic syndrome prevalences according to the prepubertal and pubertal groups were estimated by chi-square test. The differences between data were studied using the Student's t-test. The plasma glucose response and total insulin secretion were evaluated from the area under the response curve (AUC) estimated by the trapezoid rule. Statistical significance was taken as p < 0.05. All statistical analyses were

Results

A total of 169 children and adolescents aged 7–18 years underwent assessment (100 prepubertal and 69 pubertal). Mean age was 10.8 ± 3 years. The clinical characteristics of study population are provided in Table 1. Of the obese children, 32% had a positive family history for obesity and 13% for diabetes, with no differences between sexes.

According to our results from OGTT performed in 169 obese children (mean age ± S.D., 8.95 ± 2.1 years) and adolescents (mean age ± S.D., 13.4 ± 1.92 years), the total

Discussion

Recent studies reported an increased prevalence of IGT and type 2 diabetes mellitus in obese children and adolescents, especially in specific ethnic subgroups. Already, there is not enough knowledge about the prevalences of glucose abnormalities and metabolic syndrome in obese children in Turkey. Because of the geographical settling, Turkey is influenced by near-east Asia and European civilization for social, economic and socio-cultural views. By the 20th century, economical development and

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