An evaluation of the International Diabetes Federation definition of metabolic syndrome in Chinese patients older than 30 years and diagnosed with type 2 diabetes mellitus
Introduction
Metabolic syndrome (MS) is a cluster of dangerous myocardial infarction risk factors: diabetes and impaired glucose regulation, central obesity, hypertension, and dyslipidemia. People with MS are at an increased risk for cardiovascular disease and for increased mortality [1], [2], [3], [4].
Although clustering of some metabolic abnormalities was recognized as early as 1923, the coining of the term syndrome X in 1988 by Reaven [5] renewed the impetus to conducting research in this syndrome. As an understanding of the dimensions of this syndrome is critical for allocating both health care and research resources, the World Health Organization (WHO) initially proposed a definition for MS in 1998 [6] and, more recently, the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III [ATPIII]) provided a working definition of MS [7]. However, no standard definition has been routinely used, and a universally accepted definition of MS is needed, which has been demonstrated in many studies [8], [9]. In 2005, the International Diabetes Federation (IDF) published a new worldwide definition of MS intended to be applicable to various ethnic groups [10]. The new definition is similar to the ATPIII definition, but has significant difference. Notably, central obesity (defined by waist circumference with ethnic modification in its thresholds) was treated as a prerequisite risk factor for the diagnosis of the syndrome in the new definition. Lately, additional analysis from a Japan Diabetes Complications Study has shown that the new worldwide IDF definition of MS is not a better diagnostic predictor of cardiovascular disease in the Japanese diabetic patients than the existing definitions, and the new definition's lower prediction power for cardiovascular disease seemed to have been derived from the indispensability of the waist circumference component [11].
Therefore, we set out to accomplish several goals in this study. Firstly, we calculated the estimates of the prevalence of MS by applying the ATPIII, WHO, and new IDF definitions in the Chinese patients diagnosed with type 2 diabetes mellitus. Secondly, we compared the new international definition with the previous ones and evaluated the predictive power for cardiovascular disease of these definitions to determine the most accurate MS definition in the Chinese patients diagnosed with type 2 diabetes mellitus. Thirdly, we evaluated the cutoff point of waist circumference using the new definition because MS diagnosis by the new definition was highly dependent on waist circumference.
As a cross-sectional study, our study was unable to evaluate cardiovascular events prospectively, so we adopted surrogate markers for atherosclerotic cardiovascular disease. Measurement of the intima-media thickness (IMT) of carotid artery by ultrasonography is a noninvasive and quantitative method of evaluating early atherosclerotic changes in the vasculature [12], [13], [14]. Carotid artery IMT is an established risk factor and a surrogate marker for atherosclerotic cardiovascular disease [15], and an increase in carotid artery IMT is associated with an increased risk of myocardial infarction and stroke even in the absence of obstructive luminal disease of carotid arteries [16], [17], [18], [19]. Carotid plaque is also a marker of atherosclerotic change [20].
Section snippets
Study design
A cross-sectional study to evaluate the prevalence of diabetic complications in the Chinese patients older than 30 years and diagnosed with type 2 diabetes mellitus was planned in the Shanghai downtown. We selected our subjects by randomized cluster sampling. According to estimated diabetic nephropathy prevalence of 33% in China [21], [22], an admissible error of 0.03 (about 10% prevalence of diabetic nephropathy), and for a precision of 0.05, a sample of 944 patients was estimated (n = 1.962 ×
Results
A final sample of 1039 patients was investigated. A total of 1008 patients including 389 male patients and 619 female patients were analyzed in an additional analysis of diabetic complications study based on data integrity. The mean age of these 1008 patients was 66.17 ± 11.54 years and the duration of diabetes was 7.92 ± 7.17 years.
Discussion
The prevalence of MS keeps increasing in diabetic patients. The Botnia study in Finland showed that the prevalence of MS under the WHO definition in men and women was 78% and 84% in type 2 diabetic patients [33]. Another study in Europe [34] revealed that the prevalence of the MS in a population-based cohort of type 2 diabetic patients was 75.6%. However, in African diabetic patients, 2 studies indicated that the prevalence of MS was 43% [35] and 25.2% [36], respectively. Our results showed
Acknowledgment
This study was funded by grants to Renming Hu from Shanghai Science and Technology Commission (04dz19504), the Key Project of National Natural Science Foundation of China (30230380), the National Natural Science Foundation of China (39900072), the Chinese High Tech Program (2002BA711A05 and 2001AA221201), and the National Key Basic Research and Development Program (2002CB713703). We express our heartfelt thanks to Drs Jingchong Fang, Bo Mou, Fengling Chen, Min He, Yu Liu, Ye Shen, Xuanchun
References (45)
- et al.
The metabolic syndrome and risk of major coronary events in the Scandinavian Simvastatin Survival Study (4S) and the Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS)
Am J Cardiol
(2004) - et al.
Progression of carotid atherosclerosis and its determinants: a population-based ultrasonography study
Atherosclerosis
(1990) - et al.
Ultrasound-detected plaque of carotid artery as a screening tool for advanced subclinical atherosclerosis
Am Heart J
(2005) - et al.
The cardiovascular health study: design and rational
Ann Epidemiol
(1991) - et al.
Ultrasonographic measurement of the common carotid artery wall thickness in hypercholesterolemic patients: a new model for the quantitation and follow-up of preclinical atherosclerosis in living human subjects
Atherosclerosis
(1988) - et al.
Risk factors for asymptomatic atherosclerosis in Japanese type 2 diabetic patients without diabetic microvascular complications
Metabolism
(2003) - et al.
Are waist circumference and body mass index independently associated with cardiovascular disease risk in Chinese adults?
Am J Clin Nutr
(2005) - et al.
Prevalence of the metabolic syndrome and its relation to all-cause and cardiovascular mortality in non diabetic European men and women
Arch Intern Med
(2004) - et al.
The metabolic syndrome and total and cardiovascular disease mortality in middle-aged men
JAMA
(2002) - et al.
Impact of the metabolic syndrome on mortality from coronary heart disease, cardiovascular disease, and all causes in United States adults
Circulation
(2004)