Abstract 68: Interleukin-6, Diabetes and Metabolic Syndrome in a Biracial Cohort: The Reasons for Geographic and Racial Differences in Stroke (REGARDS)

Background: Type 2 diabetes mellitus (DM) is more common in Black than White adults in the US. The inflammatory cytokine interleukin-6 (IL-6) is implicated in DM pathogenesis and circulates at higher levels in Black people. Metabolic syndrome (MetS), a group of conditions related to insulin resistance, often precedes or coexists with DM. Little evidence is available on associations of IL-6 with these disorders in Black people. Methods: REGARDS enrolled 30,239 Black and White adults in 2003-07 and conducted a follow up visit 9.5 years later. Baseline IL-6 was measured in a sample of 4,400 participants (equal by race/sex groups) attending both visits. Modified Poisson regression estimated relative risk (RR) by level of baseline IL-6 for incident DM among those without prevalent DM; similar analyses were conducted for MetS. Inverse odds weighting estimated the percent mediation of the racial disparity in incident DM by IL-6. Results: Incident DM occurred in 460/3,399 (14%) at risk, and there were 384/1,957 (20%) cases of incident MetS. As shown in the Figure , DM and MetS incidence increased across baseline IL-6 quartiles overall, with a steeper rise and higher incidence among Black than White adults. Adjusting for confounders, the RR of DM for IL-6 in the 4 th vs 1 st quartile was 1.91 (95% CI 1.38-2.65). Higher IL-6 was also associated with MetS (RR 1.65 (95% CI 1.22-2.22)). In adjusted models there were no material differences in these associations by race. The RR of DM in Black compared with White people was 1.90 (95% CI 1.59-2.27); there was no association of race with MetS. IL-6 significantly mediated 13.4% of the racial disparity in DM adjusting for demographic factors. Conclusions: Higher IL-6 is a risk factor for incident DM and MetS in Black and White adults. The race disparity in DM was partly mediated by IL-6. Interventions to reduce IL-6 may lower risk of DM and MetS and lessen the racial disparity in DM. Figure: Diabetes and Metabolic Syndrome Incidence (bars) and Relative Risk (95% CI) by Baseline IL-6 Quartile