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. 2014 Dec;15(8):557-63.
doi: 10.1111/pedi.12132. Epub 2014 Mar 17.

Hemoglobin A1c assay variations and implications for diabetes screening in obese youth

Christine L Chan  1 , Kim McFann, Lindsey Newnes, Kristen J Nadeau, Philip S Zeitler, Megan Kelsey
Affiliations

Hemoglobin A1c assay variations and implications for diabetes screening in obese youth

Christine L Chan et al. Pediatr Diabetes. 2014 Dec.

Abstract

Background: Standardization of the hemoglobin A1c (A1c) assay has led to its increasing utilization as a screening tool for the diagnosis of prediabetes and type 2 diabetes in youth. However, significant A1c assay variability remains and has implications for clinical management.

Objective: To describe our center's experiences with A1c results in youth and to evaluate inter-method differences and their clinical implications.

Subjects: Seventy-five youth (aged 10-18 yr old), body mass index (BMI) ≥85th‰ participated.

Methods: Seventy-two participants had two A1c values performed on the same sample, one via immunoassay (DCA Vantage Analyzer, A1c1 ) and the other via high performance liquid chromatography (Bio-Rad Variant II, A1c2 ). Nineteen had A1c run on two immunoassay devices (A1c1 and Dimensions Vista, A1c3 ).

Results: Mean age of participants was 13.9 years, BMI% 97.89%, 33% male, 16% white, 21% black, and 61% Hispanic (H). Mean A1c1 was 5.68% ± 0.38 vs. a mean A1c2 of 5.73% ± 0.39, p = 0.049. Concordance in diabetes status between methods was achieved in 79% of subjects. Nineteen subjects with A1c3 results had testing performed an average of 22 ± 9 days prior to A1c1 . Mean A1c3 was 6.24% ± 0.4, compared to a mean A1c1 of 5.74% ± 0.31, (p < 0.0001). A1c1 was on average systematically -0.5 ± 0.28 lower compared to A1c3 . There was poor agreement in diabetes classification between A1c1 and A1c3 , with a concordance in classification between methods of only 36.8%.

Conclusions: Clinically significant inter-method A1c variability exists that impacts patient classification and treatment recommendations. In the screening of obese youth for diabetes, A1c results should be interpreted with caution.

Keywords: hemoglobin A1c; obesity; prediabetes; type 2 diabetes.

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Conflict of interest statement

The authors have no relevant disclosures or conflicts of interest.

Figures

Figure 1
Figure 1
a – Correlation between A1c1 and A1c2 b – Bland-Altman plot of the difference against the mean of A1c1 and A1c2 results
Figure 2
Figure 2
a – Correlation bewteen A1c1 and A1c3 b – Bland-Altman plot of the difference against the mean of A1c1 and A1c3 results
See this image and copyright information in PMC

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