A1C is a universally used blood test to assess glycemic control during the previous 2–3 months in patients with diabetes (1). It is used to monitor long-term glycemic control and assess patients’ response to therapy and is a quality-assessment tool for diabetes care in the United Kingdom and throughout the world (2). Hence, it is important that any condition that can affect the true value of A1C be considered in clinical practice. We report here a case series of patients attending our adult secondary care diabetes clinic, all of whom were noted to have considerably lower A1C levels than what would be expected from their daily blood glucose monitoring results. The cause for the falsely low A1C in each case was found to be drug-induced hemolysis, most commonly due to sulfasalazine use. When A1C is inaccurate, fructosamine levels can be another way of monitoring average glycemic control, particularly in patients taking drugs that cause drug-induced hemolysis (1,3). In some patients, A1C can be falsely low. Any condition that shortens the life span of red blood cells, and therefore the length of time hemoglobin is exposed to glucose in the bloodstream, can falsely lower A1C. Examples include hemolytic anemias, hemoglobinopathies, splenomegaly, blood loss, blood transfusions, chronic liver or kidney disease, and some drugs (4,5). Drugs that cause subtle hemolysis without anemia may interfere with the accuracy of A1C measurement (6). Reported examples of such drugs include dapsone, sulfasalazine, ribavirin, and antiretroviral drugs (4). There are few data from randomized, controlled studies on the subject of drug-induced hemolysis causing falsely low A1C levels; thus, there is little information about the prevalence of this phenomenon. There are, however, several case reports. The first, reported in 1979 from Kesson et al. (6), described a case of dapsone-induced hemolysis …