Background Persistent hypoglycaemia is common in the newborn and is associated with poor neurodevelopmental outcome. Adequate monitoring is critical in prevention, but is dependent on frequent, often hourly blood sampling. Continuous glucose monitoring (CGM) is increasingly being used in children with type 1 diabetes mellitus, but use in neonatology remains limited. We aimed to introduce real-time CGM to provide insights into patterns of dysglycaemia and to support the management of persistent neonatal hypoglycaemia. Methods This is a single centre retrospective study of real-time CGM use over a 4-year period in babies with persistent hypoglycaemia. Results CGMs were inserted in 14 babies: 8 term and 6 preterm infants, 9 with evidence of congenital hyperinsulinism (CHI). A total of 224 days of data were collected demonstrating marked fluctuations in glucose levels in babies with CHI, with a higher sensor glucose SD (1.52±0.79 mmol/l vs 0.77±0.22mmol/l) in infants with CHI compared to preterm infants. A total of 1254 paired glucose values (CGM and blood) were compared and gave a mean absolute relative difference (MARD) of 11%. Conclusion CGM highlighted the challenges of preventing hypoglycaemia in these babies when using intermittent blood glucose levels alone, and the potential application of CGM as an adjunct to clinical care.