Glycated haemoglobin (HbA1c) is used to monitor the long term management of diabetes and reflects the average blood glucose level over the past 3 months. HbJ is an alpha globin gene variant that occurs less commonly but can interfere with HbA1c result. This case report presents two cases of abnormally high HbA1c in diabetic patient with HbJ using High Performance Liquid Chromatography (HPLC) method and repeated value using capillary electrophoresis (CE) method. The first case was a 26 years old, female Malay patient, presenting at the gestational age of 25 weeks with diabetes mellitus (DM). Her HbA1c results from HPLC showed persistently high level (>18.5% (>179mmol/mol) despite optimum diabetic control (fasting blood sugar (FBS) range 4.0 to 6.1mmol/L). The second case was a 62 years old female Malay with Type 2 DM. Her HbA1c results from HPLC also was persistently high (>18.5% (>179mmol/mol) despite good diabetic control (FBS average 5.0 to 7.0mmol/L). Both patients’ haemoglobin (Hb) analysis report were suggestive of HbJ. Repeated HbA1c using CE principle were 6% (42mmol/mol) and 8.1% (65mmol/mol) respectively and supported the presence of HbJ variant peak. HbA1C measurement in patients with variant should be interpreted with caution to avoid misdiagnosis and mismanagement in these kinds of patients.

Glycated haemoglobin (HbA1c) is used to monitor the long term management of diabetes and reflects the average blood glucose level over the past 3 months. HbJ is an alpha globin gene variant that occurs less commonly but can interfere with HbA1c result. This case report presents two cases of abnormal...