Atypical Presentation of Metformin- induced Lactic Acidosis in a Patient with Normal Renal Function: A Case Report

Abstract

Elevated lactate levels and high anion gap metabolic acidosis are hallmarks of Metformin-associated lactic acidosis, a rare but potentially fatal complication of Metformin therapy. Although the incidence of MALA is low, it carries a significantly high mortality rate, particularly in cases where diagnosis and treatment are delayed. Early recognition is therefore essential to improve clinical outcomes and reduce the risk of fatality. MALA is most commonly associated with underlying conditions such as sepsis, hypoxia, or renal impairment, all of which can impair lactate clearance and exacerbate metabolic disturbances. However, it is important to note that MALA can also occur in the absence of these traditional risk factors, making diagnosis more challenging. This highlights the need for clinicians to maintain a high index of suspicion even in atypical presentations. In this case, a patient with type 2 diabetes mellitus who had been receiving long-term metformin therapy presented with symptoms including nausea, vomiting, and altered mental status following a short episode of fever. Despite having normal renal function, laboratory investigations revealed severe metabolic acidosis, with a blood pH of less than 7.2 and markedly elevated lactate levels. These findings are consistent with a diagnosis of MALA, suggesting that metformin accumulation or altered metabolism may have contributed to the condition. The probable cause of the patient’s metabolic disturbance was attributed to metformin, despite the absence of common predisposing factors such as renal dysfunction. This case underscores the importance of recognising that MALA can develop even in patients who appear clinically stable and do not exhibit typical risk factors. Timely identification and intervention are therefore critical in preventing severe complications and improving patient outcome.