Diabète ou pas ? Une HbA1c étrange

This case report illustrates the difficulty in the analysis and interpretation of HbA1c measurement in a patient with a moderately elevated fetal haemoglobin (HbF) level of 6.9%. This patient cumulated various cardiovascular risk factors: a biological follow-up with glycaemia measurements and HbA1c determinations was undergone. While glycaemia was always normal or subnormal, HbA1c levels (achieved in a private routine laboratory by an automated HPLC method) were consistently high and pathological. A subsequent in-hospital evaluation showed that this patient was heterozygous for beta-thalassemia accompanied with a moderately elevated HbF level. The HbA1c level assessed by an automated HPLC method with the Bio-Rad Variant II system dualkit and a 6 min total elution time was of 4.7%. This HbA1c result is in agreement with the glycaemic profile of the patient, as checked by a continuous glucose monitoring (CGMS) and an oral glucose load, corresponding to a mild glucose intolerance. The knowledge of a hemoglobinopathy like the heterozygous beta-thalassemia presented in this case is crucial for HbA1c analysis by the correct method without any interference and thus for a precise result and interpretation.