The cross-sectional Telde Study showed that the prevalence of all cardiovascular risk factors increased in patients having successively higher levels of evidence of impaired glucose regulation. The prevalence of hypertension increased from 30.1% to 34.5%, 39.6% and 55.4% among individuals with normal glucose tolerance (NGT) to isolated IFG (impaired fasting glucose), isolated IGT (impaired glucose tolerance) and IFG/IGT, respectively.
5 Likewise, mean triglyceride levels increased from 97.9 mg/dL to 109.47 mg/dL, 125.49 mg/dL and 132.61 mg/dL, respectively, and HDL-C decreased from 55.77 mg/dL to 55.38 mg/dL, 53.43 mg/dL and 51.98 mg/dL, respectively, across the four groups. Finally, using the 2005 International Diabetes Federation definition, the rate of MetSyn increased from 13.2% to 57.2%, 64.4% and 75.6%, respectively, across the four groups.
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This correlation has been demonstrated in pediatric populations as well. An evaluation of the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2006 using fasting blood glucose and two-hour postprandial glucose among participants aged 12 to 17 years of age found a high prevalence of prediabetes, defined as having IFG (fasting plasma glucose > 100 mg/dL and < 126 mg/dL), IGT (2-hour postprandial > 140 mg/dL and < 200 mg/dL). In this age group, the prevalence of IFG, IGT, and IFG or IGT (prediabetes) was 13.1%, 3.4% and 16.1%, respectively.
5 The estimated prevalence of IFG was 87.1% higher than the 7% estimated from NHANES data from 1999 to 2000; a rapid increase in the prevalence of central obesity in adolescents was considered a potential factor in this rise.
There was a strong association between the prevalence of prediabetes and adolescents who were overweight (> 95th percentile of BMI), with the frequency of prediabetes 2.6 times higher in the overweight group. In addition, there was a strong association between prediabetes and cardiometabolic risk factors, including high blood pressure, hypertriglyceridemia and central obesity, as well as hyperinsulinemia in this group. Adolescents with two of these four risk factors had a significantly higher prevalence of prediabetes, suggesting that clustering of metabolic risk factors should be used to target adolescents at higher risk for progression to type 2 diabetes mellitus and CV events.
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However, evaluating the additive risk that the thresholds of MetSyn provide to individuals over the independent risk factors shows lower yield. A study using NHANES data evaluated the association between the risk factors for MetSyn and cardiovascular disease, based on the World Health Organization (WHO) and NCEP definitions of the syndrome.
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The study used modeling to calculate long-term CVD outcomes based on each patient's risk factors. By calculating each patient's risk, the authors were able to evaluate how well the constructs of MetSyn predicted CV events. The study concluded that the use of the syndrome as a definition did not provide any more discrimination than the use of the independent risk factor evaluation. The authors found that using MetSyn added little to assessing each patient's risk of future CV events.
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Other studies have found a greater association between the presence of MetSyn than independent risk factors. A study using data from the Cardiovascular Health Study, a longitudinal registry of individuals >65 years of age sponsored by the National Heart, Lung, and Blood Institute found that using the ATP III criteria provided increased prognostic information, after adjustment for traditional CV risk factors and those included in the definition of MetSyn. The WHO criteria added more prognostic information than traditional risk factors did.
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