Continuous glucose monitoring in a neonate with hyperinsulinemic hypoglycemia and ABCC8 gene mutation

Neonatal hypoglycemia is a metabolic disorder affecting approximately 5-15% of newborns and is a risk factor for adverse neurological outcomes. The most common cause of hypoglycemia is hyperinsulinemic hypoglycemia (HH), which presents itself in two forms: transient and permanent. Permanent HH is associated with genetic factors, including monogenic forms such as ABCC8 gene mutation. In HH, proper glycemic monitoring is crucial for revealing all hypoglycemic events; therefore, continuous glucose monitoring (CGM) may benefit these patients. We report a case of a newborn with persistent severe hypoglycemia that was unresponsive to intravenous glucose administration. Due to frequent severe hypoglycemic events, we implemented CGM, decreasing the number of invasive procedures for assessing glucose concentration. Genetic testing revealed the presence of a heterozygous splicing variant in ABCC8. The patient qualified for positron emission tomography, and a diffuse form of HH was diagnosed. Consequently, the patient qualified for a full pancreatectomy. Neonatal hypoglycemia presents diagnostic challenges, as proper differential diagnosis is crucial for successful treatment. In cases of persistent HH, genetic testing should always be offered to exclude conditions requiring prompt treatment and to achieve a good long-term outcome. As some hypoglycemic events might be asymptomatic, CGM might be a better option for patients with HH, as it allows for the analysis of all glycemic fluctuations and, therefore, reduces the need for invasive procedures.

Persistent hypoglycemia in neonates requires differential diagnosis. In severe cases of HH not responding to diazoxide, positron emission tomography using 18F-fluoro-L-dihydroxyphenylalanine (18F-DOPA PET) is the test of choice to make diffuse/local HH differential diagnoses. Continuous glucose monitoring allows for quicker reaction during hypoglycemia and hyperglycemia, reducing possible complications that can affect the neonatal brain. Nowadays, there are many available resources that limit causing pain in neonates. There are reports of using CGM in neonates, but it is not registered.