Background The American Diabetes Association recommends glycosylated hemoglobin (A1C) to assess the management of diabetes mellitus (DM) and provides specific A1C goals to reduce the risk of DM-related complications. Although A1C is a convenient test to diagnose and monitor DM management over a 3-month time frame, certain conditions may affect the accuracy of the A1C. Case summary This case describes a woman diagnosed as having type 2 DM based on multiple A1C levels > 10%. The patient was treated by her primary care provider based on her A1C and was experiencing hypoglycemic and adverse events, despite a consistently elevated A1C. Discrepancies were noted between A1C results, random glucose monitoring at office visits, home blood glucose monitoring, and clinical presentation. Professional-use continuous glucose monitoring (CGM) and fructosamine levels were used to further assess the patient’s glycemic management. The patient was found to have a hemoglobin (Hb) Wayne variant by Hb electrophoresis and demonstrated a misdiagnosis of type 2 DM. Practice implications This report describes the importance of patient and clinician communication and highlights the limitations of using A1C levels that should be taken into consideration when the clinical picture does not align with the laboratory assessment. It also demonstrates the value of CGM technology for patients and offers a unique approach to using the ambulatory glucose profile report to promote engaging discussions with patients.
