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)

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 one’s 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.