Measurement of HbA1c from stored whole blood samples in the Atherosclerosis Risk in Communities study

Department of Epidemiology and the Welch Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21287, USA.
Journal of Diabetes (Impact Factor: 1.93). 06/2010; 2(2):118-24. DOI: 10.1111/j.1753-0407.2010.00070.x
Source: PubMed


The aims of the present study were to demonstrate the reliability of HbA1c measurements during two time periods and to compare these measurements with HbA1c distribution in the general US population.
HbA1c was measured in 14,069 whole blood samples in the Atherosclerosis Risk in Communities (ARIC) study using different HPLC instruments across two time periods, namely 2003-2004 and 2007-2008. At the time of measurement, samples had been in storage at -70°C for up to 18 years. To assess differences in values, HbA1c measurements were repeated in 383 samples at both periods. Indirect comparisons were made by comparing our measurements against those from a nationally representative study.
The coefficients of variation for quality control samples were 1.8% (n = 89) in 2003-2004 and 1.4% (n = 259) in 2007-2008. The correlation between measurements at the two time points was high (r = 0.99), but with a slight bias: 0.29% points higher in 2007-2008 vs 2003-2004 (n = 383; P < 0.0001). The comparison yielded the following Deming regression equation: y((2007-2008)) = 0.073 + 1.034x((2003-2004)) . After alignment using this equation, the distribution of HbA1c in the ARIC study was similar to that in the national study using fresh samples.
Measurements of HbA1c from samples stored for up to 18 years are highly reliable when using state-of-the-art HPLC instruments, but with some bias introduced over time. The HbA1c data now available in the ARIC study should be invaluable for investigations into the clinical utility of HbA1c as a diagnostic test for diabetes.

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    • "Serum glucose was measured as part of the original ARIC protocol using a hexokinase method on a Coulter DACOS (Coulter Instruments). We measured HbA1c from stored whole blood samples from all participants at ARIC visit 2 using high-performance liquid chromatography (Tosoh HbA1c 2.2 and Tosoh G7; Tosoh) (20). All values were standardized to the Diabetes Control and Complications Trial HbA1c assay. "
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    ABSTRACT: OBJECTIVE There is debate regarding the clinical significance of well-established racial differences in HbA1c. We compared the associations of diabetes diagnostic categories for HbA1c and fasting glucose with clinical outcomes in black and white persons in the community.RESEARCH DESIGN AND METHODS We conducted a prospective cohort analysis of participants without diabetes or cardiovascular disease from the Atherosclerosis Risk in Communities study. We examined the associations of clinical categories of HbA1c (<5.7%, 5.7-6.4%, ≥6.5%) and fasting glucose (<100, 100-125, ≥126 mg/dL) with outcomes separately among 2,484 black and 8,593 white participants and tested for race interactions.RESULTSBaseline characteristics differed significantly in blacks compared with whites, including HbA1c (5.8 vs. 5.4%; P < 0.001). During 18 years of follow-up, there were trends of increased risk of kidney disease, fatal and nonfatal coronary heart disease, and stroke across categories of HbA1c in both blacks and whites. The adjusted hazard ratios for each outcome across categories of HbA1c were similar in blacks and whites (P for interaction >0.05) except for all-cause mortality. Patterns of association were similar, but weaker, for fasting glucose. HbA1c and fasting glucose both were more strongly associated with all-cause mortality in whites compared with blacks, largely explained by racial differences in the rate of cardiovascular deaths.CONCLUSIONS HbA1c is a risk factor for vascular outcomes and mortality in both black and white adults. Patterns of association for HbA1c were similar to or stronger than those for fasting glucose. With respect to long-term outcomes, our findings support a similar interpretation of HbA1c in blacks and whites for diagnosis and treatment of diabetes mellitus.
    Diabetes care 05/2013; 36(10). DOI:10.2337/dc12-2715 · 8.42 Impact Factor
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    • "We collected, stored, and processed blood specimens for measurements, including fasting blood glucose, fasting insulin, hemoglobin A1c (A1c), and blood chemistries (8). We used a Glucostat analyzer (Model 27, YSA, Inc, Yellow Springs, Ohio) to measure fasting blood glucose, enzyme-linked immunosorbent assays (Mercodia, Uppsala, Sweden) to measure blood insulin levels, and GLYCO-Tek Affinity Columns (Helena Laboratories, Beaumont, Texas) to measure A1c on frozen whole blood (15). We obtained fasting lipid and liver panels and high sensitivity C-reactive protein in a Clinical Laboratory Improvement Amendments-approved medical laboratory. "
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    ABSTRACT: Diabetes, hypertension, and hypercholesterolemia are common chronic diseases among Hispanics, a group projected to comprise 30% of the US population by 2050. Mexican Americans are the largest ethnically distinct subgroup among Hispanics. We assessed the prevalence of and risk factors for undiagnosed and untreated diabetes, hypertension, and hypercholesterolemia among Mexican Americans in Cameron County, Texas. We analyzed cross-sectional baseline data collected from 2003 to 2008 in the Cameron County Hispanic Cohort, a randomly selected, community-recruited cohort of 2,000 Mexican American adults aged 18 or older, to assess prevalence of diabetes, hypertension, and hypercholesterolemia; to assess the extent to which these diseases had been previously diagnosed based on self-report; and to determine whether participants who self-reported having these diseases were receiving treatment. We also assessed social and economic factors associated with prevalence, diagnosis, and treatment. Approximately 70% of participants had 1 or more of the 3 chronic diseases studied. Of these, at least half had had 1 of these 3 diagnosed, and at least half of those who had had a disease diagnosed were not being treated. Having insurance coverage was positively associated with having the 3 diseases diagnosed and treated, as were higher income and education level. Although having insurance coverage is associated with receiving treatment, important social and cultural barriers remain. Failure to provide widespread preventive medicine at the primary care level will have costly consequences.
    Preventing chronic disease 08/2012; 9(8):110298. DOI:10.5888/pcd9.110298 · 2.12 Impact Factor
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    ABSTRACT: This study sought to investigate an association of HbA1c (A1C) with incident heart failure among individuals without diabetes and compare it to fasting glucose. We studied 11,057 participants of the Atherosclerosis Risk in Communities (ARIC) Study without heart failure or diabetes at baseline and estimated hazard ratios of incident heart failure by categories of A1C (<5.0, 5.0-5.4 [reference], 5.5-5.9, and 6.0-6.4%) and fasting glucose (<90, 90-99 [reference], 100-109, and 110-125 mg/dl) using Cox proportional hazards models. A total of 841 cases of incident heart failure hospitalization or deaths (International Classification of Disease, 9th/10th Revision, 428/I50) occurred during a median follow-up of 14.1 years (incidence rate 5.7 per 1,000 person-years). After the adjustment for covariates including fasting glucose, the hazard ratio of incident heart failure was higher in individuals with A1C 6.0-6.4% (1.40 [95% CI, 1.09-1.79]) and 5.5-6.0% (1.16 [0.98-1.37]) as compared with the reference group. Similar results were observed when adjusting for insulin level or limiting to heart failure cases without preceding coronary events or developed diabetes during follow-up. In contrast, elevated fasting glucose was not associated with heart failure after adjustment for covariates and A1C. Similar findings were observed when the top quartile (A1C, 5.7-6.4%, and fasting glucose, 108-125 mg/dl) was compared with the lowest quartile (<5.2% and <95 mg/dl, respectively). Elevated A1C (> or =5.5-6.0%) was associated with incident heart failure in a middle-aged population without diabetes, suggesting that chronic hyperglycemia prior to the development of diabetes contributes to development of heart failure.
    Diabetes 08/2010; 59(8):2020-6. DOI:10.2337/db10-0165 · 8.10 Impact Factor
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