New approaches to screening and management of neonatal hypoglycemia based on improved understanding of the molecular mechanism of hypoglycemia

A Review of Screening Guidelines for Hypoglycaemia in Infants Born Small for Gestational Age Showed Numerous Differences and Few Certainties

AIM

Different hypoglycaemia screening guidelines for infants born small for gestational age (SGA) are applied throughout the world. This narrative review analysed the published guidelines and evaluated the characteristic features of hypoglycaemia in SGA infants to assess the relevance of the issue.

METHODS

PubMed and the Cochrane Database of Systematic Reviews were reviewed for papers regarding hypoglycaemia and hypoglycaemia screening guidelines in term and near-term SGA infants. We also searched government-related websites and national healthcare institution websites for guidelines.

RESULTS

Numerous differences among guidelines were found. The American Academy of Pediatrics and the Pediatric Endocrine Society do not specify which SGA infants need screening. Other guidelines suggest screening infants with birth weight < 10th percentile, while still others < 2nd percentile. Depending on the growth curves, the SGA population may change. The hypoglycaemia cut-off value was another relevant variance. The duration of glucose level checks varies from the first 4-24 h of life. The reported incidence of hypoglycaemia was 12%-52%. The timing of hypoglycaemia onset was 2-6 h of life. Specific risk factors for hypoglycaemia in SGA infants were found.

CONCLUSION

Numerous differences were found in the hypoglycaemia guidelines for SGA infants, and further studies are needed to address strong and uniform guidance.

Role of beta-hydroxybutyrate measurement in the evaluation of plasma glucose concentrations in newborn infants

OBJECTIVE

The Glucose in Well Babies (GLOW) Study showed that there are two phases of low glucose concentrations in healthy newborn infants: an initial phase in which plasma concentrations of ketones are low; and a second phase in which low glucose concentrations are accompanied by elevated concentrations of ketones. The implications of these two phases for the brain differ depending on whether ketones are available as alternative substrate for brain metabolism. The purpose of this study was to estimate the duration of these two phases of neonatal low glucose concentrations in 66 healthy breastfed newborns from the GLOW Study during the first 5 days of life.

METHODS

The sum of glucose and beta-hydroxybutyrate (BOHB) was used as a proxy for the total concentrations of insulin-dependent fuels for the brain; a threshold value below 4 mmol/L was taken to indicate the presence of relative hyperinsulinism and a BOHB concentration above 0.5 mmol/L to indicate ketonaemia.

RESULTS

The first phase of low glucose concentrations lasted a median of 40 hours and in 15% of infants, this persisted beyond 60 hours. Fifty (76%) of the 66 infants subsequently had ketonaemia, which resolved at a median age of 76 hours (range 41->120 hours).

CONCLUSIONS

These data suggest that monitoring BOHB concentrations may be useful for interpreting glucose concentrations in newborns and screening for persistent hyperinsulinism.

Neonatal hyperinsulinism: a retrospective study of presentation and management in a tertiary neonatal intensive care unit in the UK

OBJECTIVE

Reports of hyperinsulinism typically focus on infants managed by highly specialised services. However, neonates with hyperinsulinism are initially managed by neonatologists and often not referred to specialists. This study aimed to characterise the diversity in presentation and management of these infants.

SETTING

Level 3 neonatal intensive care.

PATIENTS

Neonates with hyperinsulinism, defined as blood glucose <2.8 mmol/mL and insulin level >6 pmol/L.

DESIGN

7-year retrospective study (January 2015-December 2021).

RESULTS

99 cases were identified: severe-treated with diazoxide (20%), moderate-clinically concerning hyperinsulinism not treated with diazoxide (30%), mild-biochemical hyperinsulinism (50%). Birth weight z-score was -1.02±2.30 (mean±SD), 42% were preterm, but neither variable correlated with clinical severity. The severe group received a higher concentration of intravenous glucose (27±12%) compared with the moderate (15±7%) and mild (16±10%) groups (p<0.001). At diagnosis, the intravenous glucose intake was similar in the severe (7.43±5.95 mg/kg/min) and moderate (5.09±3.86 mg/kg/min) groups, but higher compared with the mild group (3.05+/2.21 mg/kg/min) (p<0.001). In the severe group, term infants started diazoxide earlier (9.9±4.3 days) compared with preterm (37±26 days) (p=0.002). The national congenital hyperinsulinism service was consulted for 23% of infants, and 3% were transferred.

CONCLUSIONS

This study highlights the diversity in clinical presentation, severity and prognosis of neonatal hyperinsulinism, irrespective of birth weight and gestational age. More infants were small rather than large for gestational age, and the majority had transient hyperinsulinism and were not referred to the national centre, or treated with diazoxide. Further research is required to understand the breadth of neonatal hyperinsulinism and optimal management.

Approach to the Neonate With Hypoglycemia

After birth, healthy neonates undergo a period of altered glucose metabolism, known as "transitional hypoglycemia." During the first 0 to 4 hours of life, the mean plasma glucose concentration decreases to 57 mg/dL, then by 72 to 96 hours of life increases to 82 mg/dL, well within the normal adult range. Recent data suggest that transitional hypoglycemia is due to persistence of the fetal beta cell's lower threshold for insulin release, resulting in a transient hyperinsulinemic state. While hypoglycemia is an expected part of the transition to postnatal life, it makes the identification of infants with persistent hypoglycemia disorders challenging. Given the risk of neurologic injury from hypoglycemia, identifying these infants is critical. Hyperinsulinism is the most common cause of persistent hypoglycemia in neonates and infants and carries a high risk of neurocognitive dysfunction given the severity of the hypoglycemia and the inability to generate ketones, a critical alternative cerebral fuel. Screening neonates at risk for persistent hypoglycemia disorders and completing evaluations prior to hospital discharge is essential to prevent delayed diagnoses and neurologic damage.

Etiology of the Neonatal Hypoglycemias

To provide a more appropriate foundation for dealing with the problem of hypoglycemia in newborn infants, this article focuses on the mechanisms which underlie the various forms of neonatal hypoglycemia and discusses their implications for newborn care. Evidence indicates that all of the major forms of neonatal hypoglycemia are the result of hyperinsulinism due to dysregulation of pancreatic islet insulin secretion. Based on these observations, the authors propose that routine measurement of B-hydroxybutyrate should be considered an essential part of glucose monitoring in newborn infants.

Diazoxide for Severe or Recurrent Neonatal Hypoglycemia: A Randomized Clinical Trial

Importance

Neonatal hypoglycemia is an important preventable cause of neurodevelopmental impairment, but there is a paucity of evidence to guide treatment.

Objective

To evaluate whether early, low-dose oral diazoxide for severe or recurrent neonatal hypoglycemia reduces time to resolution of hypoglycemia.

Design, Setting, and Participants

This 2-arm, placebo-controlled randomized clinical trial was conducted from May 2020 to February 2023 in tertiary neonatal units at 2 New Zealand hospitals. Participants were neonates born at 35 or more weeks' gestation and less than 1 week of age with severe hypoglycemia (blood glucose concentration <22 mg/dL or <36 mg/dL despite 2 doses of dextrose gel) or recurrent hypoglycemia (≥3 episodes of a blood glucose concentration <47 mg/dL within 48 hours).

Interventions

Newborns were randomized 1:1 to receive diazoxide suspension (loading dose, 5 mg/kg; maintenance, 1.5 mg/kg every 12 hours) or placebo, titrated per protocol.

Main Outcome and Measures

The primary outcome was time to resolution of hypoglycemia, defined as enteral bolus feeding without intravenous fluids and normoglycemia (blood glucose concentration of 47-98 mg/dL) for at least 24 hours, compared between groups using adjusted Cox proportional hazards regression. Hazard ratios adjusted for stratification variables and gestation length are reported. Prespecified secondary outcomes, including number of blood glucose tests and episodes of hypoglycemia, duration of hypoglycemia, and time to enteral bolus feeding and weaning from intravenous fluids, were compared by generalized linear models. Newborns were followed up for at least 2 weeks.

Results

Of 154 newborns screened, 75 were randomized and 74 with evaluable data were included in the analysis (mean [SD] gestational age for the full cohort, 37.6 [1.6] weeks), 36 in the diazoxide group and 38 in the placebo group. Baseline characteristics were similar: in the diazoxide group, mean (SD) gestational age was 37.9 (1.6) weeks and 26 (72%) were male; in the placebo group, mean (SD) gestational age was 37.4 (1.5) weeks and 27 (71%) were male. There was no significant difference in time to resolution of hypoglycemia (adjusted hazard ratio [AHR], 1.39; 95% CI, 0.84-2.23), possibly due to increased episodes of elevated blood glucose concentration and longer time to normoglycemia in the diazoxide group. Resolution of hypoglycemia, when redefined post hoc as enteral bolus feeding without intravenous fluids for at least 24 hours with no further hypoglycemia, was reached by more newborns in the diazoxide group (AHR, 2.60; 95% CI, 1.53-4.46). Newborns in the diazoxide group had fewer blood glucose tests (adjusted count ratio [ACR], 0.63; 95% CI, 0.56-0.71) and episodes of hypoglycemia (ACR, 0.32; 95% CI, 0.17-0.63), reduced duration of hypoglycemia (adjusted ratio of geometric means [ARGM], 0.18; 95% CI, 0.06-0.53), and reduced time to enteral bolus feeding (ARGM, 0.74; 95% CI, 0.58-0.95) and weaning from intravenous fluids (ARGM, 0.72; 95% CI, 0.60-0.87). Only 2 newborns (6%) treated with diazoxide had hypoglycemia after the loading dose compared with 20 (53%) with placebo.

Conclusions and Relevance

In this randomized clinical trial, early treatment of severe or recurrent neonatal hypoglycemia with low-dose oral diazoxide did not reduce time to resolution of hypoglycemia but reduced time to enteral bolus feeding and weaning from intravenous fluids, duration of hypoglycemia, and frequency of blood glucose testing compared with placebo.

Trial Registration

ANZCTR.org.au Identifier: ACTRN12620000129987.

Association of Fetal Catecholamines With Neonatal Hypoglycemia

Importance

Perinatal stress and fetal growth restriction increase the risk of neonatal hypoglycemia. The underlying pathomechanism is poorly understood. In a sheep model, elevated catecholamine concentrations were found to suppress intrauterine insulin secretion, followed by hyperresponsive insulin secretion once the adrenergic stimulus subsided.

Objective

To determine whether neonates with risk factors for hypoglycemia have higher catecholamine concentrations in umbilical cord blood (UCB) and/or amniotic fluid (AF) and whether catecholamines are correlated with postnatal glycemia.

Design, Setting, and Participants

In a prospective cohort study of 328 neonates at a tertiary perinatal center from September 2020 through May 2022 in which AF and UCB were collected immediately during and after delivery, catecholamines and metanephrines were analyzed using liquid chromatography with tandem mass spectrometry. Participants received postnatal blood glucose (BG) screenings.

Exposure

Risk factor for neonatal hypoglycemia.

Main Outcomes and Measures

Comparison of catecholamine and metanephrine concentrations between at-risk neonates and control participants, and correlation of concentrations of catecholamines and metanephrines with the number and severity of postnatal hypoglycemic episodes.

Results

In this study of 328 neonates (234 in the risk group: median [IQR] gestational age, 270 [261-277] days; and 94 in the control group: median [IQR] gestational age, 273 [270-278] days), growth-restricted neonates showed increased UCB median (IQR) concentrations of norepinephrine (21.10 [9.15-42.33] vs 10.88 [5.78-18.03] nmol/L; P < .001), metanephrine (0.37 [0.13-1.36] vs 0.12 [0.08-0.28] nmol/L; P < .001), and 3-methoxytyramine (0.149 [0.098-0.208] vs 0.091 [0.063-0.149] nmol/L; P = .001). Neonates with perinatal stress had increased UCB median (IQR) concentrations of norepinephrine (22.55 [8.99-131.66] vs 10.88 [5.78-18.03] nmol/L; P = .001), normetanephrine (1.75 [1.16-4.93] vs 1.25 [0.86-2.56] nmol/L; P = .004), and 3-methoxytyramine (0.120 [0.085-0.228] vs 0.091 [0.063-0.149] nmol/L; P = .008) (P < .0083 was considered statistically significant). Concentrations of UCB norepinephrine, metanephrine, and 3-methoxytyramine were negatively correlated with AF C-peptide concentration (rs = -0.212, P = .005; rs = -0.182, P = .016; and rs = -0.183, P = .016, respectively [P < .017 was considered statistically significant]). Concentrations of UCB norepinephrine, metanephrine, and 3-methoxytyramine were positively correlated with the number of hypoglycemic episodes (BG concentration of 30-45 mg/dL) (rs = 0.146, P = .01; rs = 0.151, P = .009; and rs = 0.180, P = .002, respectively). Concentrations of UCB metanephrine and 3-methoxytyramine were negatively correlated with the lowest measured BG concentration (rs = -0.149, P = .01; and rs = -0.153, P = .008, respectively).

Conclusions and Relevance

Neonates at risk for hypoglycemia displayed increased catecholamine and metanephrine concentrations that were correlated with postnatal hypoglycemic episodes and lower BG levels; these results are consistent with findings in a sheep model that fetal catecholamines are associated with neonatal β-cell physiology and that perinatal stress or growth restriction is associated with subsequent neonatal hyperinsulinemic hypoglycemia. Improving the pathomechanistic understanding of neonatal hypoglycemia may help to guide management of newborns at risk for hypoglycemia.

Proposed Screening for Congenital Hyperinsulinism in Newborns: Perspective from a Neonatal-Perinatal Medicine Group

This perspective work by academic neonatal providers is written specifically for the audience of newborn care providers and neonatologists involved in neonatal hypoglycemia screening. Herein, we propose adding a screen for congenital hyperinsulinism (CHI) by measuring glucose and ketone (i.e., β-hydroxybutyrate (BOHB)) concentrations just prior to newborn hospital discharge and as close to 48 h after birth as possible, at the same time that the mandated state Newborn Dried Blood Spot Screen is obtained. In the proposed protocol, we do not recommend specific metabolite cutoffs, as our primary objective is to simply highlight the concept of screening for CHI in newborns to newborn caregivers. The premise for our proposed screen is based on the known effect of hyperinsulinism in suppressing ketogenesis, thereby limiting ketone production. We will briefly discuss genetic CHI, other forms of neonatal hypoglycemia, and their shared mechanisms; the mechanism of insulin regulation by functional pancreatic islet cell membrane KATP channels; adverse neurodevelopmental sequelae and brain injury due to missing or delaying the CHI diagnosis; the principles of a good screening test; how current neonatal hypoglycemia screening programs do not fulfill the criteria for being effective screening tests; and our proposed algorithm for screening for CHI in newborns.

Neonatal Hypoglycemia

Neonatal hypoglycemia (NH) is broadly defined as a low plasma glucose concentration that elicits hypoglycemia-induced impaired brain function. To date, no universally accepted threshold (reference range) for plasma glucose levels in newborns has been published, as data consistently indicate that neurologic responses to hypoglycemia differ at various plasma glucose concentrations. Infants at risk for NH include infants of diabetic mothers, small or large for gestational age, and premature infants. Common manifestations include jitteriness, poor feeding, irritability, and encephalopathy. Neurodevelopmental morbidities associated with NH include cognitive and motor delays, cerebral palsy, vision and hearing impairment, and poor school performance. This article offers a timely discussion of the state of the science of NH and recommendations for neonatal providers focused on early identification and disease prevention.

Association between glycemic variability and short-term mortality in patients with acute kidney injury: a retrospective cohort study of the MIMIC-IV database

Acute kidney injury (AKI) represents a significant challenge to global public health problem and is associated with poor outcomes. There is still considerable debate about the effect of mean blood glucose (MBG) and coefficient of variation (CV) of blood glucose on the short-term mortality of AKI patients. This retrospective cohort study aimed to explore the association between glycemic variability and short-term mortality in patients with AKI. Data from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database were analyzed, including 6,777 adult AKI patients. MBG and CV on the first day of ICU admission were calculated to represent the overall glycemic status and variability during the ICU stay in AKI patients. The primary outcome indicator was ICU 30-day mortality of AKI patients. Multivariate Cox regression analysis and smoothed curve fitting were used to assess the relationship between blood glucose levels and mortality. Eventually, the ICU 30-day mortality rate of AKI patients was 23.5%. The increased MBG and CV were significantly correlated with ICU 30-day mortality (hazards ratio (HR) = 1.20, 95% confidence interval (CI) 1.14-1.27; HR = 1.08, 95% CI 1.03-1.13). The smoothed curve fitting showed a U-shaped relationship between MBG on the first day of ICU admission and ICU 30-day mortality (inflection point = 111.3 mg/dl), while CV had a linear relationship with 30-day ICU mortality. Thus, we conclude that MBG and CV were significantly associated with short-term mortality in intensive care patients with AKI. Tighter glycemic control may be an effective measure to improve the prognosis of patients with AKI.

The Rising Incidence of Hyperinsulinemic Hypoglycemia: Connection With Maternal Health

OBJECTIVE

Due to a perceived rise in hyperinsulinemic hypoglycemia (HH) cases over time, notably during the COVID-19 pandemic, institutional experiences between 2013 and 2021 were reviewed to evaluate trends, characteristics, and outcomes in children with HH.

METHODS

Charts of all children diagnosed with HH during the study period and evaluated by Pediatric Endocrinology were reviewed. HH was defined per Pediatric Endocrine Society guidelines. Regression analysis compared rates of change in HH cases and maternal risk factors over time.

RESULTS

The incidence of HH began to rise in April 2016 and became significant in March 2017 (P < .001), with a more rapid rate of rise during the first year of the COVID-19 pandemic (P < .001). Seventy-four children with HH were identified over 9 years; 43% (n = 32) were diagnosed in 2020-2021. Maternal hypertensive disorders demonstrated longitudinal association with hyperinsulinism cases (P < .001).

CONCLUSION

While HH diagnoses were on the rise for much of the 9-year study period, nearly half of all infants were diagnosed during the COVID-19 pandemic in 2020 to 21. The trends in HH diagnoses correlated with maternal hypertensive disorders. More studies exploring the roles of maternal health, hypertension, and stress and development of HH in offspring are needed.

Development of a prediction model for neonatal hypoglycemia risk factors: a retrospective study

Background

It's challenging for healthcare workers to detect neonatal hypoglycemia due to its rapid progression and lack of aura symptoms. This may lead to brain function impairment for the newborn, placing a significant care burden on the family and creating an economic burden for society. Tools for early diagnosis of neonatal hypoglycemia are lacking. This study aimed to identify newborns at high risk of developing neonatal hypoglycemia early by developing a risk prediction model.

Methods

Using a retrospective design, pairs (470) of women and their newborns in a tertiary hospital from December 2021 to September 2022 were included in this study. Socio-demographic data and clinical data of mothers and newborns were collected. Univariate and multivariate logistic regression were used to screen optimized factors. A neonatal hypoglycemia risk nomogram was constructed using R software, and the calibration curve and receiver operator characteristic curve (ROC) was utilized to evaluate model performance.

Results

Factors integrated into the prediction risk nomogram were maternal age (odds ratio [OR] =1.10, 95% CI: 1.04, 1.17), fasting period (OR=1.07, 95% CI: 1.03, 1.12), ritodrine use (OR=2.00, 95% CI: 1.05, 3.88), gestational diabetes mellitus (OR=2.13, 95% CI: 1.30, 3.50), gestational week (OR=0.80, 95% CI: 0.66, 0.96), fetal distress (OR=1.76, 95% CI: 1.11, 2.79) and neonatal body mass index (OR=1.50, 95% CI: 1.24, 1.84). The area under the curve (AUC) was 0.79 (95% confidence interval [CI]: 0.75, 0.82), specificity was 0.82, and sensitivity was 0.62.

Conclusion

The prediction model of this study demonstrated good predictive performance. The development of the model identifies advancing maternal age, an extended fasting period before delivery, ritodrine use, gestational diabetes mellitus diagnosis, fetal distress diagnosis and an increase in neonatal body mass index increase the probability of developing neonatal hypoglycemia, while an extended gestational week reduces the probability of developing neonatal hypoglycemia.