Falsely low glycosylated haemoglobin levels probably secondary to hypersplenism in a patient with diabetes mellitus

A man in his 70s presented with a history of low glycated haemoglobin (HbA1c) values despite a diagnosis of type 2 diabetes. His blood glucose readings ranged between 8 and 15 mmol/L, but his HbA1c values were below 27 mmol/mol. Initial investigations demonstrated evidence of reduced red blood cell lifespan as a cause of misleadingly low HbA1c values. Further investigation revealed chronic liver disease and splenomegaly, with hypersplenism being the probable cause of increased red blood cell turnover. HbA1c estimation was no longer reliable, so ongoing diabetic care was guided by home capillary blood glucose monitoring. Healthcare providers and clinical laboratorians need to be aware of the possible clinical implications of very low HbA1c values in patients with type 2 diabetes.