| Background and objective Metabolically obese, normal-weight(MONW) individuals were those whose BMI (weight in kilograms divided by the square of height in meters) was considered normal but who develop some obesity-related cardiometabolic disorders, including visceral fat accumulation, impaired glucose regulation, aggregation of insulin resistance, as well as dyslipidemia and high blood pressure. Eventually, they were found at increased risk of type 2 diabetes and cardiovascular disease. Although a formal definition has not been developed, some researches have found that MONW is highly prevalent. Therefore, it is important to discriminate MONW individuals from normal-weight population in order to more effectively prevent cardiometabolic disorders. The aim of this study was to determine the prevalence, characteristics and risk factors of MONW in Shandong province.Methods A cross-sectional study was conducted from June 2007 to May 2008 in Jinan city, Jining city, Zibo city and Taian city, Shandong province. Excluding those with a BMI≥25 kg/m2 from the total 3011 subjects, one thousand six hundred and eleven subjects aged 20-84 years old were enrolled. Questionnaire survey, physical examination and biochemical test were detected and analyzed. Those with a BMI<25 kg/m2 but fulfill the criteria of metabolic syndrome defined by the American Heart Association/National Heart, Lung and Blood Institute (2005), were defined as MONW. SPSS 16.0 software used for statistical analysis. Measurable data was showed as mean±standard deviation (SD).χ2 test was used to compare rates. Multivariable logistic regression model was used to analyze the related factors to MONW. P<0.05 was considered statistically significant.SPSS 16.0 was used to analyze the data.Results1. The unadjusted and age-adjusted prevalence of metabolic syndrome in Shandong population with a BMI<25 kg/m2 was 23.2% and 19.8%, which was higher than that of other ethnicities.2. Compared with non-MONW group, the MONW subjects had higher mean values of age, waist circumference, BMI, waist circumference, blood pressure, fasting sugar,30 minutes postprandial plasma glucose, (30minPG) two-hour postprandial plasma glucose(2hPG), fasting insulin (FINS), two-hour postprandial insulin(2hINS), total cholesterol, triglyceride, LDL-c and urinary microalbulin, while they had lower concentration of 30 minutes postprandial plasma insulin(30minINS) and HDL-c. They were significantly different between the MONW group and non-MONW group.3. Among the factors entered into multivariable logistic regression models, female gender, age, dietary history, education and BMI were the related factors for MONW.4. The higher the BMI categories, the more prevalent the metabolic syndrome was both in women and in men (P<0.01). Compared with those with a BMI≤18.5 kg/m2, the odds ratios for metabolic syndrome were 5.9 (95% CI: 1.3-26.7) with BMI 18.5-20.9 kg/m2,13.4 (3.1-58.4) with BMI 21.0-22.9 kg/m2, and 23.1 (5.3-100.3) with BMI 23.0-24.9 kg/m2, after controlling for confounding factors.5. The prevalence increased significantly at the BMI cutoff of 23 kg/m2 in men (P=0.002), and 21 kg/m2 in women (P<0.001).Conclusions This study showed that the prevalence of MONW in non-obese Chinese was relatively higher than other races, indicating that Chinese were susceptible to this disorder. We found an unfavorable metabolic profile in MONW subjects, placing them at an increased risk for type 2 diabetes and cardiovascular disease. Individuals in the upper normal weight and slightly overweight BMI range have relatively high prevalence and increased risk of having metabolic syndrome. Therefore, physicians should screen metabolic syndrome in not only obese but also non-obese individuals for the prevention of cardiovascular disease. Changes or improvements in the life style and various risk factors of MONW subjects might have potential benefits to reversing their metabolic abnormalities. |
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