Chaoyang Li

OBJECTIVE: We examined the prevalences of diagnosed diabetes, and undiagnosed diabetes and pre-diabetes using fasting and 2-h oral glucose tolerance test values, in the U.S. during 2005-2006. We then compared the prevalences of these conditions with those in 1988-1994. RESEARCH DESIGN AND METHODS: In 2005-2006, the National Health and Nutrition Examination Survey included a probability sample of 7,267 people aged > or =12 years. Participants were classified according to glycemic status by interview for diagnosed diabetes and by fasting and 2-h glucoses measured in subsamples. RESULTS: In 2005-2006, the crude prevalence of total diabetes in people aged > or =20 years was 12.9%, of which approximately 40% was undiagnosed. In people aged > or =20 years, the crude prevalence of impaired fasting glucose was 25.7% and of impaired glucose tolerance was 13.8%, with almost 30% having either. Over 40% of individuals had diabetes or pre-diabetes. Almost one-third of the elderly had diabetes, and three-quarters had diabetes or pre-diabetes. Compared with non-Hispanic whites, age- and sex-standardized prevalence of diagnosed diabetes was approximately twice as high in non-Hispanic blacks (P < 0.0001) and Mexican Americans (P = 0.0001), whereas undiagnosed diabetes was not higher. Crude prevalence of diagnosed diabetes in people aged > or =20 years rose from 5.1% in 1988-1994 to 7.7% in 2005-2006 (P = 0.0001); this was significant after accounting for differences in age and sex, particularly in non-Hispanic blacks. Prevalences of undiagnosed diabetes and pre-diabetes were generally stable, although the proportion of total diabetes that was undiagnosed decreased in Mexican Americans. CONCLUSIONS: Over 40% of people aged > or =20 years have hyperglycemic conditions, and prevalence is higher in minorities. Diagnosed diabetes has increased over time, but other conditions have been relatively stable.

OBJECTIVE: Our objective was to perform a quantitative review of prospective studies examining the association between the metabolic syndrome and incident diabetes. RESEARCH DESIGN AND METHODS: Using the title terms "diabetes" and "metabolic syndrome" in PubMed, we searched for articles published since 1998. RESULTS: Based on the results from 16 cohorts, we performed a meta-analysis of estimates of relative risk (RR) and incident diabetes. The random-effects summary RRs were 5.17 (95% CI 3.99-6.69) for the 1999 World Health Organization definition (ten cohorts); 4.45 (2.41-8.22) for the 1999 European Group for the Study of Insulin Resistance definition (four cohorts); 3.53 (2.84-4.39) for the 2001 National Cholesterol Education Program definition (thirteen cohorts); 5.12 (3.26-8.05) for the 2005 American Heart Association/National Heart, Lung, and Blood Institute definition (five cohorts); and 4.42 (3.30-5.92) for the 2005 International Diabetes Federation definition (nine cohorts). The fixed-effects summary RR for the 2004 National Heart, Lung, and Blood Institute/American Heart Association definition was 5.16 (4.43-6.00) (six cohorts). Higher number of abnormal components was strongly related to incident diabetes. Compared with participants without an abnormality, estimates of RR for those with four or more abnormal components ranged from 10.88 to 24.4. Limited evidence suggests fasting glucose alone may be as good as metabolic syndrome for diabetes prediction. CONCLUSIONS: The metabolic syndrome, however defined, has a stronger association with incident diabetes than that previously demonstrated for coronary heart disease. Its clinical value for diabetes prediction remains uncertain.

BACKGROUND: The association between concentrations of uric acid and the metabolic syndrome in children and adolescents remains incompletely understood. The objective of this study was to examine how these 2 were associated in a nationally representative sample of US children and adolescents. METHODS AND RESULTS: We performed a cross-sectional analysis of 1370 males and females aged 12 to 17 years using data from the National Health and Nutrition Examination Survey 1999-2002. The prevalence of the metabolic syndrome was < 1% among participants in the lowest quartile of serum concentration of uric acid, 3.7% in the second quartile, 10.3% in the third quartile, and 21.1% in the highest quartile. Compared with the lowest 2 quartiles of uric acid together (< or = 291.5 micromol/L), the odds ratios were 5.80 (95% confidence interval, 3.22 to 10.46) for those in the third quartile (> 291.5 to < or = 339 micromol/L or > 4.9 to < or = 5.7 mg/dL) and 14.79 (95% confidence interval, 7.78 to 28.11) for those in the top quartile (> 339 micromol/L) after adjustment for age, sex, race or ethnicity, and concentrations of C-reactive protein. Starting with the lowest quartile of concentration of uric acid, mean concentrations of serum insulin were 66.2, 66.7, 79.9, and 90.9 pmol/L for ascending quartiles, respectively (P for trend <0.001). CONCLUSIONS: Among US children and adolescents, serum concentrations of uric acid are strongly associated with the prevalence of the metabolic syndrome and several of its components.

OBJECTIVES: Abdominal obesity may be a better predictor than overall obesity for the risk of cardiovascular disease and type 2 diabetes. Waist circumference and waist-height ratio are 2 simple, yet effective, surrogate measures of abdominal obesity. We sought to examine the recent trends in mean waist circumference and waist-height ratio and prevalence of abdominal obesity among children and adolescents aged 2 to 19 years in the United States. METHODS: Representative samples of the civilian, noninstitutionalized US population from the National Health and Nutrition Examination Survey conducted during 4 time periods, 1988-1994 (ie, National Health and Nutrition Examination Survey III), 1999-2000, 2001-2002, and 2003-2004, were examined to estimate the mean waist circumference and waist-height ratio of boys and girls in 4 different age groups. Data from the 3 most recent National Health and Nutrition Examination Surveys were combined to establish a National Health and Nutrition Examination Survey 1999-2004 category. RESULTS: Categorized by age group, the unadjusted mean waist circumference for boys increased between National Health and Nutrition Examination Survey III and National Health and Nutrition Examination Survey 1999-2004 from 50.7 cm (aged 2-5 years), 61.9 cm (aged 6-11 years), 76.8 cm (aged 12-17 years), and 81.3 cm (aged 18-19 years) to 51.9, 64.5, 79.8, and 86.6 cm, respectively. During the same time periods and within the same age groups, the unadjusted mean waist circumference for girls increased from 51.0, 61.7, 75.0, and 77.7 cm to 51.8, 64.7, 78.9, and 83.9 cm, respectively. The relative change in waist-height ratio was similar to waist circumference at each age group for both boys and girls. Using the 90th percentile values of waist circumference for gender and age, the prevalence of abdominal obesity increased by 65.4% (from 10.5% to 17.4%) and 69.4% (from 10.5% to 17.8%) for boys and girls, respectively. CONCLUSIONS: Mean waist circumference and waist-height ratio and the prevalence of abdominal obesity among US children and adolescents greatly increased between 1988-1994 and 1999-2004.