MON-LB025 An Artificially Low HbA1c as a Result of Dapsone Therapy

Since the 1970s, hemoglobin A1c (HbA1c) has been incorporated in clinical practice to monitor glycemic control. Furthermore, in 2010, the American Diabetes Association included HbA1c as a diagnostic criterion for diabetes. According to Zion Market Research, the global HbA1c market is expected to reach 2.2 billion USD by 2021. HbA1c is useful to clinicians because it provides a broader perspective of a patient’s glycemic control compared to the snapshot granted by blood glucose measurement. The erythrocyte membrane is permeable to glucose, allowing the sugar to react nonenzymatically with the N-terminal amino group of the beta chain via a ketoamine linkage. This process occurs continuously over the erythrocyte lifetime, which results in HbA1c representing a three-month window which reflects patients’ glycemic control. However, instances exist in which the utility of HbA1c diminishes in diabetic monitoring. We present the 8(th) case report in which dapsone interfered with the ability of HbA1c to accurately depict the glycemic status of a patient. The patient is a Caucasian male who was started on dapsone therapy on December 9(th), 2013 for lichen planus. HbA1c values ranged from 7.2-8.9% during the four years before initiation of dapsone therapy. Two months after dapsone was started, HbA1c dropped to 6.9% and subsequently remained at 4.8%-5.8% until the drug was discontinued on May 11(th), 2016. Three months later, HbA1c levels increased to 7.6% and ranged from 7.3%-7.8% until June the following year. In addition, fingerstick glucose values during this period also suggested poor glycemic control. Because HbA1c levels decreased in the presence of elevated fingerstick glucose, fructosamine levels were analyzed. Fructosamine refers to proteins that are nonenzymatically glycated via ketoamine linkages at the N-amino terminal (Danese et al 2015). Because albumin is the major serum protein, fructosamine primarily reflects glycated albumin. As opposed to erythrocytes, albumin exists in the blood for about two weeks. Therefore, fructosamine, indicates recent glycemic status for a narrower window than HbA1c. On July 23(rd), 2015 the patient’s fructosamine levels were 299 mcmol/L (reference range: 200-285 mcmol/L) while HbA1c was 4.9%. As a result, the fructosamine results suggest that the patient’s glycemic control had not improved as suggested by the HbA1c values. A side effect of dapsone is hemolytic anemia. During the time that the patient was on dapsone, his hemoglobin levels dropped from about 14 g/dL to 11.7 g/dL. Simultaneously, total bilirubin levels increased from approximately 0.5 mg/dL to 0.9 mg/dL, suggesting a hemolytic anemia. We propose that dapsone generated a hemolytic anemia in this patient, which caused his HbA1c values to be unreliable in monitoring his glycemic control. Clinicians should be wary when monitoring the course of diabetic disease in patients on dapsone therapy. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.