Haemoglobin A(1C) Levels Constantly Below Lower Reference Limit in a Diabetic Patient With Microcytic Anaemia

INTRODUCTION: Haemoglobin A(1C) (A(1C)), as a parameter of long-term glycaemic control, has been adopted to guide diabetic therapy all over the world. However, falsely high or low A(1C) could be troublesome in daily practice. CASE DESCRIPTION: A 75-year-old male diabetic patient affected by a reasonably inferred life-long history of microcytic anaemia was found to have abnormally low A(1C) values in the previous 5 months. Subsequent laboratory assessment with brilliant cresyl blue staining and haemoglobin electrophoresis detected haemoglobin H disease as the underlying cause of both the microcytic anaemia and the disturbed A(1C) measurement. DISCUSSION: Enhanced erythrocyte destruction such as in haemoglobin H disease could explain a falsely decreased A(1C) level very well. Upon facing a questionable A(1C) value, physicians dealing with diabetes should consider the possibility of undiscovered underlying causes rather than too tightly glycaemic control. LEARNING POINTS: Haemoglobin A(1C) values lower than the normal range most likely do not mean too good a control of blood sugar in diabetic patients. Careful investigation to find the underlying causes is mandatory to provide well-qualified medical care. Various haemoglobinopathies with chronic haemolysis should be considered as the background reason, especially in an endemic area for thalassaemia.