Haemoglobin A_1C Levels Constantly Below Lower Reference Limit in a Diabetic Patient With Microcytic Anaemia

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.

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.

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.

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.