Continuous Glucose Monitoring and Cerebral Oxygenation in Preterm Infants

Background - Hypoglycaemia is a very common event during the first week of life, it affects up to 15% of term newborns and it is more frequent in preterm and IUGR (Intrauterine Growth Restriction with birth weight <10th percentile) infants.

Repeated and prolonged hypoglicemic events are associated with impaired neurodevelopment outcomes in preterm infants and should be diagnosed and treated promptly (Tam EWY et al, J Pediatrics 2012; Duvanel et al, J Ped 1999; Lucas et al BMJ; 1988; Filam PM et al, J Pediatr 2006).

Unfortunately, the management of hypo / hyperglycaemias in these groups is still controversial due to the lack of Continuous Glucose Monitoring System's (CGMS) efficacy assessments in the Neonatal Care Intensive Units.

Nevertheless, recent studies indicate that CGMS is reliable and can identify a significant number of hypoglycaemias (<40mg / dl, duration> 30 minutes) which could not be recognized through traditional glycemic monitoring (Pertierra Cortada et al, J Ped 2014; Beardsall et al, Arch Dis Child Fetal\&Neonatal Ed 2013).

The reliability of data provided by CGMS were highlighted by Beardsall and colleagues (Beardsall et al, Arch Dis Child Fetal \& Neonatal Ed 2013) on a population of newborns with an average birth weight of 1007 gr (SD 0.27) and a gestational age of 28.36 SG (SD 2.26), the study showed a high correlation (0.94) between capillary monitoring data (traditional) and data provided by the CGMS.

However, the effects of these CGMS-based approaches on short and long-term neurodevelopment are still unknown, as well as the real impact of these glycemic variations and the maintenance of euglycemia on cerebral hemodynamics.

Indeed, every treatment proposed in this fragile population must have, as its ultimate aim, the improvement of its neuro-cognitive development in order to be considered effective and useful.

Aim - The study the Investigators are going to conduct is aimed to evaluate if CGM, as driver of therapeutic decisions in preterm newborns (birthweight ≤1500g, gestational age ≤32 weeks) during the first week of life, may be able to improve both short-term and long-term neurodevelopment.

Study design - Randomized Controlled Trial

• Patients: newborns with GA ≤32weeks and/or BW≤ 1500 g. They will be enrolled within the first 48 hours of life
• Intervention group: Unblinded CGM + Proportional integrative Derivative algorithm (PID) to adequate daily glucose intake
• Control group: Blinded CGM with daily glucose intake adequated according to SMBG (=2 blood glucose/day) using standard of care (ESPGHAN) intakes
• Primary Outcome: to evaluate if the use of CGMS (Continuous glucose monitoring system) combined with an algorithm for glucose infusion reduces the number of hemodynamically significant hypoglycemic events during the first week of life

Matherials and Methods - Continuous glucose sensor (Medtronic guardian) will be applied within 48 hours from birth to the study population on the lateral side of thigh, after parents' consent collection.

All the patients will be randomized to the blinded or unblinded group before the application of CGM. Randomization will be performed using a randomization list electronically generated.

Near-infrared diffuse optical tomography (DOT) will be used for brain monitoring. The instrumentation consists of:

• A cap, similar to the one we already created and used in a pilot study in this population (Galderisi et al., Neurophotonics 2016)
• Optical fibers, connected to the instrumentation and inserted into specific holes for optodes placed in the cap
• An external device containing lasers and detectors, controlled by a portable personal computer

Blinded group: they will wear CGM for 5 days, the alarms and the CGM monitor will be switched off. The daily amount of carbohydrates will be decided according to blood glucose tests (at least 2 per day).

Unblinded group (intervention/open CGM group): they will wear CGM for 5 days, the alarms of CGM will be switched on. The daily intake of carbohydrates will be adapted according to CGM data. In case of reported hypoglicaemia (<47 mg/dl), the data will be confirmed by capillary / catheter blood sampling and it wil be treated with Dextrose 40% gel (200 mg/kg) or 2 mg/kg 10% glucose solution.

Glucose adjustment for values out of the target tight glycemic range (72-144mg/dL) will be decided according to the PID algorithm and performed every 3 hours as suggested by the algorithm.

Numerosity: the estimated numerosity is 60 patients. (30 per arm)

Reasons for study interruption: local and/or systemic complication due to the application of device, transfer of patient to another center of care, withdrawal of consent, death, malfunction of device. Reasons for interruption of monitoring will be specified in the final report.

Risks and benefits analysis - The open CGM is expected to decrease the duration and number of hypoglicemic episodes. Early detection of the hypoglicemic events helps reducing their frequency, while adaptation of carbohydrate intake based on CGM data will prevent further hypoglycemic episodes during the observation period.

In addition, this device permits to reduce the number of blood sampling in the U-CGM group, reducing a painful (heel stick) and potentially dangerous (catheter sampling) procedure.

Even though the risk of local reaction is conceivable, it has never been described in studies conducted in newborns. If a local reaction occurs, the device will be removed and the trial will end for the patient.

Perspective and limits - Although the use of the CGMS in preterm infants has been well described, its efficacy in improving short-term and long-term neurodevelopment has never been established, as well as the connection between glycaemic variations and cerebral activity in this population. Only by achieving this goal the real efficacy and utility of CGMS in this population will be clear.

The study has been designed as a no-profit research project by the Principal Investigators and Collaborators of Neonatal Intensive Care Unit of University of Padua.

Interim assessment: after 20 participants enrolled; subsequent interim assessment have been planned every 20 participants enrolled. Study will be interrupted if >10% difference in primary outcome.

Funding: STARS grant from University of Padova (Italy); Penta Foundation; CARIPARO