Prevalence of the metabolic syndrome among US middle-aged and older adults with and without diabetes--a preliminary analysis of the NHANES 1999-2002 data

Abstract

Objective: This study examined the racial differences in the distribution of the individual and clustered metabolic syndrome components among diabetics and nondiabetics and the presence of inflammatory markers.

Study design and method: This is a secondary data analysis of the National Health and Nutrition Examination Survey (NHANES) from 1999-2002. The analysis only included adults aged > or = 40 years who were White, Black, and Mexican American. Differences in the rate of metabolic syndrome, each of its components, and inflammation markers among the three racial groups were examined by using chi-square tests.

Results: An estimated 12 million adults > or = 40 years of age have diagnosed and undiagnosed diabetes. Most diabetics have metabolic syndrome (69.9% for Whites, 64.8% for Blacks, and 62.4% for Mexican Americans). Abdominal obesity is more prevalent among Whites with diabetes than Mexican Americans (80.6% vs 67.8%, P = .008). Hypertension is significantly greater among Blacks with diabetes (73.1%) as compared to Whites (58.6%) and Mexican Americans (50.8%); hypertension in those without diabetes was 47.5% among Blacks, 32.4% among Whites, and 23.4% among Mexican Americans. Among nondiabetics, Blacks have higher prevalence of elevated serum C-reactive protein (17.4%) and high plasma fibrinogen (49.7%) than Whites (9.7% and 36%, respectively).

Conclusion: These data demonstrate racial differences in the prevalence of components of the metabolic syndrome among diabetics and nondiabetics. They raise questions about the current definition of the metabolic syndrome, which weights each component equally. Further research is necessary to more precisely quantify the characteristics of metabolic syndrome in different racial and ethnic groups.