Relationship of C-Reactive Protein, Metabolic Syndrome and Diabetes Mellitus: CRP and Metabolic Dysfunction in Nonwhite Populations

28 Nov

CRP and Metabolic Dysfunction in Nonwhite Populations

It is more common in African Americans than in whites, probably due to both genetic and environmental risk factors. Moreover, African Americans have a higher risk of the microvascular complications of diabetes than do whites, possibly due to a higher prevalence of preexisting high blood pressure. Whereas chronic inflammation is associated with insulin resistance, which is a component of metabolic syndrome, the role played by inflammation in the pathogenesis of metabolic dysfunction and diabetes in nonwhites is just beginning to be studied.

The clustering of metabolic and inflammation variables was investigated using factor analysis of data from 1,087 nondiabetic participants in the

IRAS. Findings identified three underlying factors that significantly predicted type-2 diabetes in multivariate analysis. Factor patterns—relationships among metabolic, inflammatory and blood pressure factors and risk of incident diabetes—were similar in separate analyses of African-American, Hispanic and non-Hispanic white subjects, suggesting that the underlying mechanisms that cause metabolic and inflammatory variables to cluster are not greatly modified by ethnicity. However, among the 288 African Americans in this analysis, no significant prediction of diabetes was seen using inflammation factors.

In a subanalysis from the Atherosclerosis Risk in Communities (ARIC) study, stored plasma from 581 incident cases of diabetes and 572 noncases were ana­lyzed for the presence of the inflammatory markers sialic acid, orosomucoid, IL-6 and CRP, and the corre­lation of these markers with diabetes. An overall inflammation score based on these markers plus white blood cell count and fibrinogen was found to predict diabetes (buy avandia treat high blood sugar levels called type 2 diabetes) in whites but not in African Americans. The cause of this difference remains unexplained, but it may be that the character of systemic inflammation differs according to ethnicity. Clearly, in view of the great burden of diabetes and CVD in African Americans, ethnic differences in measures of inflammation and their relationship to metabolic syndrome variables and diabetes require further study.

Figure 1. Median CRP levels

Figure 1. Median CRP levels and associated interquartile range according to racial/ethnic group among participants in the Women’s Health Study

The distribution of CRP levels was compared among 24,455 white, 475 black, 357 Asian and 254 Hispanic women participating in the Women’s Health Study. Black women in the study had a higher BMI and were more likely to have hypertension and diabetes. As shown in Figure 1, median CRP levels were significantly higher among black women than among women of other racial/ethnic groups (2.96 mg/L vs. 2.02 mg/L for white, 2.06 mg/L for Hispanic and 1.12 mg/L for Asian women). BMI was a significant predictor of elevated CRP levels among all racial/ethnic groups (PO.001), but the effect was most pronounced in black women. CRP levels were higher among all women taking hormone-replacement therapy (Figure 1), although black women were less likely to be using hormones than were women in the other racial/ethnic groups. These data are consistent with the fact that adipose tissue secretes IL-6, which, in turn, stimulates production of CRP. Thus, BMI appears to account for the higher CRP levels among African-American women.