Falsely decreased HbA1c in a type 2 diabetic patient treated with dapsone

Abstract

Glycated hemoglobin A1c (HbA1c) is an important indicator of glycemic control. The current recommendation for glycemic control based on HbA1c values has been widely accepted. However, HbA1c values depend on the lifespan of erythrocytes and the assay methods used. Here, we report the case of a patient with type 2 diabetes with unusual falling of HbA1c due to interference from dapsone treatment for leukocytoclastic vasculitis. He was a 52-year-old man, who was diagnosed with type 2 diabetes mellitus 5 years previously and who had been treated in our hospital in the past 3 years. Glycemia was controlled by sulfonylurea and metformin. During the 3-years follow-up period, HbA1c dropped significantly during the addition of dapsone treatment, although plasma glucose levels remained stable. HbA1c levels were raised after discontinuation of dapsone. With rechallenge of dapsone usage, HbA1c decreased again. We conclude that dapsone may be the cause of artificially low HbA1c. Other measurements to monitor glycemic control should be considered when dapsone is used for the treatment of concurrent disorders, such as autoimmune disease and pneumocystis jiroveci pneumonia.

Falsely Decreased Hba1c in A Type 2 Diabetic Patient Treated with Dapsone

“…Today, it is used as an indicator of glycemic control and as a diagnostic test for diabetes mellitus (4). HbA 1c is formed by nonenzymatic condensation of glucose with the N-terminal valine residue of the β chains of hemoglobin (4,5). Therefore, HbA 1c reflects the glucose level an erythrocyte has been exposed to during its lifespan and is a measure of glycemic control over the last 3 months, with the immediately preceding 30 days contributing 50% to the HbA 1c (4).…”

“…These measurements help guide treatment decisions. However, HbA 1c values depend both on erythrocyte lifespan and assay methods (5). Therefore, conditions and medications that affect red blood cell turnover and erythrocyte lifespan lead to false measurements of HbA 1c (6).…”

“…There are several case reports of falsely low HbA 1c levels in patients on dapsone, including reports of patients infected with the human immunodeficiency virus (8,9), patients with autoimmune and skin conditions (5,10–14), transplant patients (15), and patients on dapsone therapy for other reasons, such as necrobiosis lipoidica and leprosy (12,16–18). …”

“…While we do not have measures of hemolysis in our patient, her hemoglobin dropped about 1 g/dL from baseline after initiation of dapsone, and 1 month after cessation of the drug, her hemoglobin increased by about 2 g/dL and has remained at this level, suggesting that the dapsone was inducing hemolysis. In addition, prior case reports demonstrated that patients on dapsone have elevated reticulocyte counts and elevated lactate dehydrogenase levels, which are indicative of hemolysis (5,9,11,12,14,17,18). Hemolysis does not always result in anemia (9), although most patients on dapsone do experience a 1 to 2 g/dL reduction in hemoglobin (5,8,12).…”

“…In addition, prior case reports demonstrated that patients on dapsone have elevated reticulocyte counts and elevated lactate dehydrogenase levels, which are indicative of hemolysis (5,9,11,12,14,17,18). Hemolysis does not always result in anemia (9), although most patients on dapsone do experience a 1 to 2 g/dL reduction in hemoglobin (5,8,12). Therefore, hemolysis can lead to a misleadingly low HbA 1c by reducing erythrocyte lifespan.…”