Interleukin-6, diabetes, and metabolic syndrome in a biracial cohort: the Reasons for Geographic and Racial Differences in Stroke cohort

Abstract

<p dir="ltr"><b>Objective: </b>Black Americans have a greater risk of type-2 diabetes than White Americans. The proinflammatory cytokine interleukin-6 (IL-6) is implicated in diabetes pathogenesis and is higher in Black people. This study investigated associations of IL-6 with incident diabetes and metabolic syndrome in a biracial cohort.</p><p dir="ltr"><b>Research Design and Methods</b><b>: </b>The REasons for Geographic And Racial Differences in Stroke study enrolled 30,239 Black and White adults age 45+ in 2003-07, with a follow-up ~9.5 years later. Baseline plasma IL-6 was measured in 3,399 at risk for incident diabetes and 1,871 for metabolic syndrome. Modified Poisson regression estimated relative risk (RR) by IL-6 for both.</p><p dir="ltr"><b>Results:</b> Incident diabetes occurred in 14% and metabolic syndrome in 20%; both rose across IL-6 quartiles. There was a 3-way interaction of IL-6, <a href="" target="_blank">race, and central adiposity for incident diabetes (</a>p=8 x10<sup>-5</sup>). In Black participants with and without central adiposity <a href="" target="_blank">RRs were 2.02 (95% CI 1.00-4.07) and 1.66 (1.00-2.75) for the 4th compared to 1st quartile of IL-6, respectively. The corresponding RRs were 1.73 (0.92-3.26) and 2.34 (1.17-4.66) in White participants. </a>The pattern was similar for IL-6 and metabolic syndrome.</p><p dir="ltr"><b>Conclusions: </b>While IL-6 was higher in Black than White participants and those with central adiposity,<b> </b>associations of IL-6 with diabetes risk was only statistically significant among White participants without central adiposity. Associations with metabolic syndrome risk were similarly stronger in low-risk groups. Results support the concept of interventions to lower inflammation in diabetes prevention, but to reduce race disparities, better biomarkers are needed.</p>