Prevalence of metabolic syndrome in obese Turkish children and adolescents
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.
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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
References (42)
- et al.
Type 2 diabetes among North American children and adolescents: an epidemiologic review and a public health perspective
J Pediatr
(2000) Contributions of insulin-resistance and insulin-secretory defects to the pathogenesis of type 2 diabetes mellitus
Mayo Clin Proc
(2003)- et al.
Pathogenic factors of glucose intolerance in obese Japanese adolescents with type 2 diabetes
Metabolism
(2000) - et al.
Adiposity in childhood predicts obesity and insulin resistance in young adulthood
J Pediatr
(2001) - et al.
Puberty decreases insulin sensitivity
J Pediatr
(1987) - et al.
Does hyperglycemia or hyperinsulinaemia characterize the patient with chemical diabetes?
Lancet
(1972) - et al.
Comparison of a low-fat diet to a low-carbohydrate diet on weight loss, body composition, and risk factors for diabetes and cardiovascular disease in free-living, overweight men and women
J Clin Endocrinol Metab
(2004) - et al.
Cardiovascular endocrinology. 2: obesity and risk of type 2 diabetes and cardiovascular disease in children and adolescents
J Clin Endocrinol Metab
(2003) - et al.
A two-step strategy for identification of high-risk subjects for a clinical trial of prevention of NIDDM
Diab Care
(1996) - et al.
Population-based study of diabetes and risk characteristics in Turkey
Diab Care
(2002)