The purpose of this study is to determine whether continuous glucose monitoring (CGM) improves the detection and management of neonatal hypoglycaemia in newborns of mothers with insulin-treated gestational diabetes.

Gestational diabetes mellitus (GDM) is a form of glucose intolerance affecting up to 14% of pregnant women and is associated with an increased risk of multiple maternal and fetal complications. This risk is proportional to the degree of maternal hyperglycaemia. Appropriate glycaemic control and dietary management are key components of GDM treatment. However, in approximately 10-30% of cases, pharmacological therapy is required, due to persistent fasting hyperglycaemia.

Neonatal hypoglycaemia is one of the most common metabolic complications associated with GDM, affecting approximately 5-15% of newborns, and is linked to increased morbidity. There is currently no universal consensus regarding the lowest safe blood glucose threshold required to prevent neurological complications in this population. Nevertheless, persistent or recurrent hypoglycaemia, that is unresponsive to treatment is known to be associated with adverse neurological outcomes.

Following birth and umbilical cord clamping, the newborn must maintain glucose homeostasis through endogenous production via glycogenolysis and gluconeogenesis, as well as through enteral feeding. This physiological transition results in lower blood glucose concentrations during the first 4 hours of life and increases the risk of neonatal hypoglycaemia. Furthermore, in pregnancies complicated by insulin-treated GDM, chronic maternal hyperglycaemia leads to hypertrophy of the fetal pancreatic islets and fetal hyperinsulinaemia, which further increases the risk of hypoglycaemia after birth.

Current clinical guidelines rely on intermittent capillary blood glucose measurements performed at predetermined intervals. However, this scheduled testing approach may fail to detect transient hypoglycaemic episodes.

Continuous glucose monitoring (CGM) enables continuous measurement of interstitial glucose concentrations. Despite its potential advantages, there is limited evidence regarding the clinical significance of CGM use in neonates born to mothers with insulin-treated gestational diabetes.

The aim of this study is to determine whether CGM improves the detection and management of neonatal hypoglycaemia in newborns of mothers with insulin-treated gestational diabetes. This study is designed as a single-centre, randomised controlled trial conducted at the Department of Neonatology and Neonatal Intensive Care, Institute of Mother and Child, Warsaw, Poland.

In the intervention group (CGM group), glucose concentrations will be monitored using CGM. Routine scheduled capillary blood glucose measurements will not be performed unless clinically indicated.

In the control group (standard monitoring group), glucose concentrations will be measured using capillary blood glucose testing in accordance with the local standard protocol. A CGM sensor will also be applied; however, glucose recordings will be masked to both clinical staff and parents.

In both groups, CGM will continuously collect glucose data for the first 72 hours after birth.

Inclusion Criteria:

• Maternal age of 18 years or older
• Singleton pregnancy
• Insulin-treated gestational diabetes mellitus

Exclusion Criteria:

• Multifetal pregnancy
• Congenital malformations or metabolic defects in the newborn
• Preterm birth (defined as birth <37 weeks of gestation)
• Smoking during pregnancy
• Preeclampsia, fetal growth restriction
• Perinatal asphyxia
• Congenital infections in the newborn
• Adverse skin reactions (eczema, wounds) in the planned sensor insertion area

In the control group, CGM data are not visible to the clinical team and do not influence clinical management.