Class effect of erythropoietin therapy on hemoglobin A(1c) in a patient with diabetes mellitus and chronic kidney disease not undergoing hemodialysis.

In patients with diabetes mellitus, hemoglobin A(1c) (A1C) is commonly interpreted as a measure of long-term glycemic control, reflecting a mean glucose level over the previous 2-3 months. Although some reports suggest that treatment with recombinant erythropoietin may affect A1C values in patients undergoing hemodialysis, we know of no evidence to support this interaction in patients with chronic renal insufficiency who are not undergoing hemodialysis. In addition, we know of no evidence specific to the treatment effect of epoetin alfa and/or darbepoetin alfa on A1C. We describe a 64-year-old man with diabetes, chronic kidney disease, and anemia who was treated consecutively with epoetin alfa and darbepoetin alfa and experienced a temporal reduction in A1C level to a nadir of 4.4%. Throughout approximately 3 years of treatment with these erythropoietin analogs, the patient's total daily dose of insulin was reduced in response to his decreasing A1C values, despite elevated blood glucose levels and the absence of patient-reported hypoglycemic events. Five months after the patient's erythropoietin therapy was discontinued, his A1C value increased to 8.8%, leading us to conclude that management of the insulin dose may have been different without the falsely lowered A1C levels. Use of the Naranjo adverse drug reaction probability scale indicated a probable association between this patient's reduced A1C levels and erythropoietin therapy. This case demonstrates that both epoetin alfa and darbepoetin alfa may artificially lower A1C levels in a patient with diabetes who is not undergoing dialysis, and therefore this finding can be interpreted as a class effect. Clinicians should be aware of factors that affect A1C values, specifically erythrocyte life span. In patients receiving erythropoietin, therapeutic decisions should be based on A1C and glucose levels, as well as patient symptoms suggestive of hypo- or hyperglycemia, to avoid therapy changes that could complicate disease management.