Decreased HbA1c Levels Due to Sulfonamide-Induced Hemolysis in Two IDDM Patients

Cees J Tack; Jack F Wetzels

doi:10.2337/diacare.19.7.775

Case Report

Decreased HbA_1c Levels Due to Sulfonamide-Induced Hemolysis in Two IDDM Patients

Cees J Tack and
Jack F Wetzels

Department of Medicine, Divisions of General Internal Medicine and Nephrology, University Hospital Nijmegen Nijmegen, The Netherlands

Address correspondence and reprint requests to Cees J.J. Tack, MD, Division of General Internal Medicine, Department of Medicine, University Hospital Nijmegen, Geert Grooteplein Zuid 8, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands. E-mail: e.tack{at}aig.azn.nl

Diabetes Care 1996 Jul; 19(7): 775-776. https://doi.org/10.2337/diacare.19.7.775

Abstract

Regular measurement of HbA_1c (percentage) is an essential component of modern diabetes care. Factors that affect the life span of erythrocytes will also influence HbA_1c results. In this study, we describe two patients with IDDM, whose regularly determined HbA_1c values were considerably decreased with the concomitant use of two related sulfonamide drugs, sulfasalazine and dapsone. The fall in HbA_1c results is explained by increased erythrocytopoiesis as a product of drug-induced hemolysis. Fructosamine concentrations are not affected by hemolysis and reflected glycemic control better. We conclude that under conditions of persistent (subclinical) hemolysis, as occurs during the use of sulfonamides, HbA_1c is not a reliable indicator of glycemic control.