Hereditary spherocytosis, a pitfall in the assessment of glycaemic control.

The use of glycosylated haemoglobin in the assessment of diabetic control is ubiquitous. Hereditary spherocytosis is a haemolytic anaemia with shortened red blood cell lifespan, which can interfere with the methods of glycosylated haemoglobin measurement. We report a case of hereditary spherocytosis in a young man with type 1 diabetes, and illustrate the discrepancy in the measurements of glycosylated haemoglobin, which were inconsistent with the blood glucose profiles. Fructosamine, an alternative time-averaged indicator of blood glucose level, was advantageous in this particular situation. The awareness of the limitations of glycosylated haemoglobin is essential in the clinical care of patients with diabetes, which is a major health problem in Singapore.