Neonatal Diabetes Mellitus Masquerading as Sepsis in a Nigerian Infant: A Case Report

Abstract

Neonatal diabetes mellitus (NDM) is a rare monogenic disorder presenting within the first six months of life. It is frequently under-recognised in low-resource settings due to its clinical overlap with severe sepsis. We report an 11-week-old Nigerian infant who presented with fever, respiratory distress, convulsions, severe dehydration, and altered consciousness, and was initially managed as severe bronchopneumonia with sepsis. Subsequent evaluation revealed marked hyperglycaemia (random blood glucose >33.5 mmol/L), metabolic acidosis (serum bicarbonate 11 mmol/L), and ketonuria, confirming diabetic ketoacidosis (DKA). The persistence and severity of hyperglycaemia beyond expected stress responses raised suspicion of an underlying metabolic disorder. The patient was managed with intravenous fluids, insulin therapy, and antibiotics, followed by careful metabolic stabilisation, after which a structured transition from insulin to oral glibenclamide was undertaken, resulting in sustained glycaemic control. In the absence of genetic testing, the favourable clinical and biochemical response to sulfonylurea therapy provided functional support for the diagnosis of NDM. The child has remained stable on follow-up care for two years. This case highlights the diagnostic challenge posed by the overlap between sepsis and metabolic disorders in early infancy and underscores the importance of routine glucose assessment in critically ill infants.