Deceived by Elevated A1C: Cases of Misdiagnosed Diabetes

A1C is an integrated biomarker for diagnosing diabetes and evaluating glycemic control in people with an established diabetes diagnosis. It has been recommended as one of the diagnostic screening criteria for more than a decade, both by the American Diabetes Association (ADA) and the World Health Organization (WHO) (1–3). However, the use of A1C as a diagnostic and monitoring tool is not without pitfalls. Conditions associated with increased or decreased erythrocyte turnover affect the A1C fraction (4), and in such cases, A1C may not reflect true average plasma glucose (5,6). Furthermore, analytical interference with A1C may occur because of genetic hemoglobin variants or metabolic alterations of hemoglobin (e.g., acetylation by acetylsalicylic acid) (7,8).