Wen-Chih Wu1,2, Mary E Lacy2, Adolfo Correa3, Mercedes Carnethon4, Alexander P Reiner5, Charles B Eaton2, Gregory A Wellenius2. 1. Division of Cardiology, Providence Veterans Affairs Medical Center, Providence, Rhode Island, USA. 2. Department of Epidemiology, Brown University School of Public Health, Providence, Rhode Island, USA. 3. Department of Medicine, University of Mississippi Medical Center, Jackson, Mississippi, USA. 4. Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA. 5. Department of Epidemiology, University of Washington School of Public Health, Seattle, Washington, USA.
Abstract
Background: 1.1.It was reported that Hemoglobin A1c (HbA1c) values of African-Americans (AAs) were on average higher than whites whereas AAs with Sickle-Cell-Trait (SCT) had lower HbA1c values compared to AAs without SCT despite controlling for average glycaemia. We evaluated the HbA1c-glucose relationship between AAs with and without SCT, and whites using data from two cohort studies. Methods: 1.2.We pooled data from Coronary-Artery-Risk-Development-Study-in-Young-Adults (CARDIA, n= 5,115, 2005-2011) and the Jackson-Heart-Study (JHS, n=5,301, 2000-2013). Whole exome sequencing in JHS and TaqMan-SNP-Genotyping Assays in CARDIA determined the SCT status in AAs. HbA1c was measured by two NGSP-certified assays without reportedly clinically significant interference from hemoglobin S. Participants without data on SCT or with hemoglobin SS, CC or AC were excluded, resulting in 6,623 participants (n=3,575 from CARDIA and n=3,048 from JHS). Generalized-estimating-equations estimated the cross-sectional association between fasting glucose and HbA1c(outcome) amongst whites, AAs with SCT, and AAs without SCT controlling for clinical-demographic factors. Results: 1.3.Our analyses included 2,003 whites, 4,253 AAs without SCT and 367 AAs with SCT. AAs with and without SCT had similar clinical-demographic characteristics, whereas whites have lower fasting- and 2-hour-glucose values than AAs. Despite higher fasting-glucose values in AAs with SCT versus whites, their HbA1c values were similar (p=0.39). In the subset with 2-hour-glucose values, HbA1c values in AAs with SCT were lower than whites (p=0.007) despite higher 2-hour-glucose values. Conclusions: 1.4.AAs with SCT have at least similar, if not lower, levels of mean HbA1c values than whites despite higher levels of glycaemia. Future research is warranted to assess whether these findings translate to clinical outcomes.
Background: 1.1.It was reported that Hemoglobin A1c (HbA1c) values of African-Americans (AAs) were on average higher than whites whereas AAs with Sickle-Cell-Trait (SCT) had lower HbA1c values compared to AAs without SCT despite controlling for average glycaemia. We evaluated the HbA1c-glucose relationship between AAs with and without SCT, and whites using data from two cohort studies. Methods: 1.2.We pooled data from Coronary-Artery-Risk-Development-Study-in-Young-Adults (CARDIA, n= 5,115, 2005-2011) and the Jackson-Heart-Study (JHS, n=5,301, 2000-2013). Whole exome sequencing in JHS and TaqMan-SNP-Genotyping Assays in CARDIA determined the SCT status in AAs. HbA1c was measured by two NGSP-certified assays without reportedly clinically significant interference from hemoglobin S. Participants without data on SCT or with hemoglobin SS, CC or AC were excluded, resulting in 6,623 participants (n=3,575 from CARDIA and n=3,048 from JHS). Generalized-estimating-equations estimated the cross-sectional association between fasting glucose and HbA1c(outcome) amongst whites, AAs with SCT, and AAs without SCT controlling for clinical-demographic factors. Results: 1.3.Our analyses included 2,003 whites, 4,253 AAs without SCT and 367 AAs with SCT. AAs with and without SCT had similar clinical-demographic characteristics, whereas whites have lower fasting- and 2-hour-glucose values than AAs. Despite higher fasting-glucose values in AAs with SCT versus whites, their HbA1c values were similar (p=0.39). In the subset with 2-hour-glucose values, HbA1c values in AAs with SCT were lower than whites (p=0.007) despite higher 2-hour-glucose values. Conclusions: 1.4.AAs with SCT have at least similar, if not lower, levels of mean HbA1c values than whites despite higher levels of glycaemia. Future research is warranted to assess whether these findings translate to clinical outcomes.
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