Introduction: Diabetic ketoacidosis (DKA) is characterized by presence of high anion-gap metabolic acidosis. Occasionally, a normal anion-gap metabolic acidosis (NAGMA) can be seen, especially during treatment phase which can complicate treatment and patient outcome. Case report: A 55 year old lady with diabetes mellitus presented with a 2 day history of fever, lethargy and multiple episodes of vomiting and diarrhea. Initial laboratory investigations revealed: capillary blood glucose 27 mmol/L, urine ketone3+, blood ketone 3.5 mmol/L, serum bicarbonate 14 mmol/L, and serum chloride 95 mmol/L. She was promptly treated with intravenous normal saline fluid resuscitation and constant rate insulin infusion which fortunately accompanied by stabilization of blood glucose and normalization of blood ketone to 0.2 mmol/L. However, despite normalization of her anion gap (30 to 14), she remained unwell with acidotic breathing due to refractory hyperchloraemic NAGMA with bicarbonate11mol/L, carbon dioxide 20 mm Hg and chloride 112 mmol/L. It was then decided to administer 100 mL of 8.4% sodium bicarbonate solution. The next day, she was no longer tachypneic as her bicarbonate and carbon dioxide improved to 21 mmol/L and 32 mm Hg respectively. She was discharged well after 2 week of hospitalization upon completion of antibiotics for Escherichia coli bacteraemia. Discussion and conclusion We hope that our case report highlighted the importance for clinicians to be aware of NAGMA which can be observed in certain cases of DKA. Its presence should prompt a thorough search for possible underlying causes, such as gastrointestinal fluid loss, sepsis and chloride load from aggressive fluid resuscitation with normal saline. Sodium bicarbonate should only be considered in intractable cases to correct a NAGMA and not routinely used in treatment of DKA. Finally, serum bicarbonate should not be used as a sole marker of DKA resolution as overzealous fluid resuscitation in setting of refractory acidosis can lead to complications and adverse patient outcome.