A falling HbA1c is not necessarily an indicator of improving diabetes control

The finding of a very low haemoglobin A1c (HbA1c) (1.4%) in a diabetic patient with fairly high plasma glucose levels prompted haematological investigations, which revealed auto-immune haemolysis and a Hb concentration of 7.7 g/L. Following treatment, both Hb and HbA1c concentrations increased roughly in parallel until, 4 months later, Hb was 13.8 g/L, HbA1c 5.2% and plasma glucose was 6.8 mmol/L. This case illustrates that a falling HbA1c cannot always be attributed to improving glucose control in diabetic patients.