Discordance Between Self-Reported and Lab-Measured A1C Among U.S. Adults with Diabetes: Findings from the National Health and Nutrition Examination Survey (2013-2020)

Abstract

Aims: To: 1) compare characteristics of those who report knowing their hemoglobin A1C (A1C) value versus those who do not; 2) determine the correlation and concordance between self-reported and lab-measured A1C; and 3) examine factors associated with a lab-measured A1C of <= 7%. Methods: This was a cross-sectional secondary data analyses of the National Health and Nutrition Examination Survey from 2013-2020. Participants >= 20 years old who reported receiving a diabetes diagnosis were included. Results: After proper sample weighting, twenty-two percent of participants reported not knowing their A1C value. Not knowing ones A1C value was associated with identifying as a racial or ethnic group other than White, having a lower income, and having less formal education (P values < 0.5). Self-reported A1C was moderately correlated with lab-measured A1C (r = 0.62, P < 0.001). Higher self-reported A1C and identifying as Black or Mexican American were associated with lower odds of good glycemic control. Conclusions: Many patients with diabetes did not know their A1C, and among those that did, the value was often inaccurate. Even when patients knew their A1C, the correlation between self-reported and lab-measured A1C was only moderate. Clinicians should evaluate and, if needed, enhance patient knowledge of A1C.