Hyperglycemia accentuates and ketonemia attenuates hypoglycemia-induced neuronal injury in the developing rat brain

Association of early dysglycemia with intraventricular hemorrhage and mortality in very low birth weight infants

To investigate the combined effect of hyperglycemia and hypoglycemia on intraventricular hemorrhage (IVH) and mortality recognizing that previous research has predominantly focused on examining these conditions independently. This study included very preterm infants who were born at King Saud Medical City, a tertiary referral center, and admitted to a level 3 neonatal intensive care unit between January 2020 and January 2024. Modified log-Poisson regression with generalized linear models and a robust variance estimator (Huber-White) were used to adjust for potential confounding factors. A total of 554 infants met the inclusion criteria. Hyperglycemia and/or hypoglycemia developed in 75.5% (418) patients within the first postnatal week. During the study period, IVH occurred in 28.5% (N = 158), and severe IVH occurred in 13% (72) infants. In addition, 13.7% (76) of infants died during the study period. The multivariate regression revealed an association between the isolated hyperglycemia, combined exposure of hypo- and hyperglycemia, and development of IVH (relative risk [RR], 2.10; 95% confidence interval [CI], 1.36, 3.25; RR, 2.33; 95% CI, 1.34, 4.06, respectively). Severe IVH was significantly associated with isolated hyperglycemia (adjusted relative risk [aRR], 2.46; 95% CI, 1.16, 5.23). Death was associated with combined hypo- and hyperglycemia (adjusted hazardous ratio [aHR], 3.19; 95% CI, 1.23, 8.26).Conclusion: Combined hyper- and hypoglycemia in the first week of life of premature babies increases the risk and severity of IVH and neonatal mortality.

Intravenous Dextrose for the Treatment of Neonatal Hypoglycaemia: A Systematic Review

INTRODUCTION

Hypoglycaemic neonates are usually admitted to neonatal intensive care for intravenous (IV) dextrose infusion if increased feeding and dextrose gel fail to restore normoglycaemia. However, the effectiveness of this intervention is uncertain. This review aimed to assess the evidence for the risks and benefits of IV dextrose for treatment of neonatal hypoglycaemia.

METHODS

Four databases and three clinical trial registries were searched from inception to October 5, 2023. Randomised controlled trials (RCTs), non-randomised studies of interventions, cohort studies, and before and after studies were considered for inclusion without language or publication date restrictions. Risk of bias was assessed using Cochrane's Risk of Bias 2 tool or Risk of Bias in Non-Randomized Studies of Interventions tool. Certainty of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation approach. Meta-analysis was planned but not carried out due to insufficient data.

RESULTS

Across 6 studies (two RCTs and four cohort), 711 participants were included. Evidence from one cohort study suggests IV dextrose treatment may not be associated with neurodevelopmental impairment at ≥18 months of age (no effect numbers, p > 0.2; very low certainty evidence; 60 infants). Evidence from one RCT suggests IV dextrose treatment may reduce the likelihood of repeated hypoglycaemia (risk ratio [RR]: 0.67 [95% CI: 0.20, 2.18], p = 0.5; low certainty evidence; 80 infants) compared to treatment with oral sucrose bolus. However, the risk of a hyperglycaemic episode may be increased (RR: 2.33 [95% CI: 0.65, 8.39], p = 0.19; 80 infants).

CONCLUSION

More evidence is needed to clarify the benefits and risks of IV dextrose for treatment of neonatal hypoglycaemia.

Hypoglycaemia and hyperglycaemia in neonatal encephalopathy: a systematic review and meta-analysis

IMPORTANCE

Although hypoglycaemia and hyperglycaemia represent the most common metabolic problem in neonates, there is still uncertainty regarding the effects of glucose homoeostasis on the neurological outcomes of infants with neonatal encephalopathy (NE).

OBJECTIVE

To systematically investigate the association between neonatal hypoglycaemia and hyperglycaemia with adverse outcome in children who suffered from NE.

STUDY SELECTION

We searched Pubmed, Embase and Web of Science databases to identify studies which reported prespecified outcomes and compared infants with NE who had been exposed to neonatal hypoglycaemia or hyperglycaemia with infants not exposed.

DATA ANALYSIS

We assessed the risk of bias (ROBINS-I), quality of evidence (Grading of Recommendations, Assessment, Development and Evaluation (GRADE)) for each of the studies. RevMan was used for meta-analysis (inverse variance, fixed effects).

MAIN OUTCOME

Death or neurodevelopmental outcomes at 18 months of age or later.

RESULTS

82 studies were screened, 28 reviewed in full and 12 included. Children who were exposed to neonatal hypoglycaemia had higher odds of neurodevelopmental impairment or death (6 studies, 685 infants; 40.6% vs 25.4%; OR=2.17, 95% CI 1.46 to 3.25; p=0.0001). Neonatal exposure to hyperglycaemia was associated with death or neurodisability at 18 months or later (7 studies, 807 infants; 46.1% vs 28.0%; OR=3.07, 95% CI 2.17 to 4.35; p<0.00001). These findings were confirmed in the subgroup analysis, which included only the infants who underwent therapeutic hypothermia.

CONCLUSIONS

These data suggest that neonatal hypoglycaemia and hyperglycaemia may be associated with the neurodevelopmental outcome later on in infants with NE. Further studies with long-term follow-up are needed to optimise the metabolic management of these high-risk infants.

PROSPERO REGISTRATION NUMBER

CRD42022368870.

Cerebral Effects of Neonatal Dysglycemia

This article summarizes the available evidence reporting the relationship between perinatal dysglycemia and long-term neurodevelopment. We review the physiology of perinatal glucose metabolism and discuss the controversies surrounding definitions of perinatal dysglycemia. We briefly review the epidemiology of hypoglycemia and hyperglycemia in fetal, preterm, and term infants. We discuss potential pathophysiologic mechanisms contributing to dysglycemia and its effect on neurodevelopment. We highlight current strategies to prevent and treat dysglycemia in the context of neurodevelopmental outcomes. Finally, we discuss areas of future research and the potential role of continuous glucose monitoring.

Strategies to improve neurodevelopmental outcomes in babies at risk of neonatal hypoglycaemia

Neonatal hypoglycaemia is associated with adverse development, particularly visual-motor and executive function impairment, in childhood. As neonatal hypoglycaemia is common and frequently asymptomatic in at-risk babies-ie, those born preterm, small or large for gestational age, or to mothers with diabetes, it is recommended that these babies are screened for hypoglycaemia in the first 1-2 days after birth with frequent blood glucose measurements. Neonatal hypoglycaemia can be prevented and treated with buccal dextrose gel, and it is also common to treat babies with hypoglycaemia with infant formula and intravenous dextrose. However, it is uncertain if screening, prophylaxis, or treatment improves long-term outcomes of babies at risk of neonatal hypoglycaemia. This narrative review assesses the latest evidence for screening, prophylaxis, and treatment of neonates at risk of hypoglycaemia to improve long-term neurodevelopmental outcomes.

Prolonged transitional neonatal hypoglycaemia: characterisation of a clinical syndrome

BACKGROUND

We performed a case-control study to characterise infants with "prolonged transitional hypoglycaemia".

METHODS

Cases were born ≥36 weeks' gestation; had ≥1 hypoglycaemic episode <72 h and ≥72 h; received ongoing treatment for hypoglycaemia ≥72 h; and were without congenital disorders or acute illness. Cases were compared to controls born ≥36 weeks' with brief transitional hypoglycaemia, resolving <72 h.

RESULTS

39/471 infants screened met case definition: 71.8% were male, 61.5% were small-for-gestational-age (SGA), and most were admitted <6 h. Compared to controls (N = 75), key risk factors for prolonged transitional hypoglycaemia were SGA (OR = 6.4, 95%CI 2.7-15.1), severe/recurrent hypoglycaemia <24 h (OR = 16.7, 95%CI 4.5-16.1), intravenous glucose bolus <24 h (OR = 26.6, 95%CI 9.4-75.1) and maximum glucose delivery rate <48 h of ≥8 mg/kg/min (OR = 25.5, 95%CI 7.7-84.1).

CONCLUSIONS

Infants with prolonged transitional hypoglycaemia are predominantly male, SGA and have early severe/recurrent hypoglycaemia requiring glucose boluses and high glucose delivery rates in the first 24-48 h.

Neonatal Hypoglycemia and Brain Vulnerability

Neonatal hypoglycemia is a common condition. A transient reduction in blood glucose values is part of a transitional metabolic adaptation following birth, which resolves within the first 48 to 72 h of life. In addition, several factors may interfere with glucose homeostasis, especially in case of limited metabolic stores or increased energy expenditure. Although the effect of mild transient asymptomatic hypoglycemia on brain development remains unclear, a correlation between severe and prolonged hypoglycemia and cerebral damage has been proven. A selective vulnerability of some brain regions to hypoglycemia including the second and the third superficial layers of the cerebral cortex, the dentate gyrus, the subiculum, the CA1 regions in the hippocampus, and the caudate-putamen nuclei has been observed. Several mechanisms contribute to neuronal damage during hypoglycemia. Neuronal depolarization induced by hypoglycemia leads to an elevated release of glutamate and aspartate, thus promoting excitotoxicity, and to an increased release of zinc to the extracellular space, causing the extensive activation of poly ADP-ribose polymerase-1 which promotes neuronal death. In this review we discuss the cerebral glucose homeostasis, the mechanisms of brain injury following neonatal hypoglycemia and the possible treatment strategies to reduce its occurrence.

Transitional Hypoglycaemia Management in Small for Gestational Age Neonates with Sucrose Enriched Expressed Breastmilk in Resource Poor Setting

AIM

To find out if oral sucrose is as efficacious as intravenous dextrose (IVDx) in treating hypoglycaemia in small for gestational age (SGA) neonates and to compare risk of feed intolerance (FI) and necrotizing enterocolitis (NEC) in oral therapy with IVDx therapy.

METHODS

Eighty SGA haemodynamically stable hypoglycaemic [blood sugar (BS) < 40 mg/dl] neonates of ≥32 to ≤36 week gestational age were randomized to receive oral sugar enriched expressed breastmilk (EBM; Group A) or IV dextrose therapy (Group B; 40 in each group) in similar calculated doses. BS at 6 h after treatment, incidence of recurrence of hypoglycaemia, FI and NEC were compared.

RESULTS

Mean BS level at 6 h after treatment in oral supplementation group was 63.53 ± 22.12 mg/dl [3.52 ± 1.22 mmol/l (IQR 49.2-82 mg/dl, 2.7-4.5 mmol/l) vs. 71.28 ± 31.76 mg/dl [3.96 ± 1.76 mmol/l (IQR 48.5-73 mg/dl, 2.69-4 mmol/l) in IVDx group, p = 0.209. Relative risk (RR) of recurrence of hypoglycaemia in oral vs. IV treatment was 1.5 with 95% CI 0.4578-4.9151. Incidence of FI (p = 0.49, RR 1, 95%CI 0.3-3.1) and NEC (p = 0.4, RR 0.2, 95%CI 0.01-4.2) was comparable.

CONCLUSION

In resource poor setting in haemodynamically stable hypoglycaemic SGA neonates, EBM enriched with calculated dose of sucrose given orally maintains euglycaemia (BS 40-125mg/dl, 2.2-6.9 mmol/l) without increased incidence of FI and NEC. This method also prevents lactational failure.

Identifying risk effectors involved in neonatal hypoglycemia occurrence

Hypoglycemia is a common metabolic condition in neonatal period, but severe and persistent hypoglycemia can cause neurological damage and brain injury. The aim of the present study was to analyze the risk factors of neonatal hypoglycemia in clinic. A total of 135 neonatal hypoglycemia infants and 135 healthy infants were included in the present study. The differences in birth weight between neonatal hypoglycemia group and healthy control group were analyzed via t test. The associations between neonatal blood sugar level and relevant characteristic factors were explored using χ2 test. Binary logistic regression analysis was used to analyze risk factors related to the incidence of neonatal hypoglycemia. The results showed that the average birth weight was matched in neonatal hypoglycemia group and healthy control group. Neonatal blood sugar level of the infants was significantly associated with born term, birth weight, feed, gestational diabetes mellitus (GDM) and hypothermia (all P<0.05). Besides, logistic regression analysis showed that babies' born term (odds ratio (OR) = 2.715, 95% confidence interval (95% CI): 1.311-5.625), birth weight (OR = 1.910, 95% CI: 1.234-2.955), improper feeding (OR = 3.165, 95% CI: 1.295-7.736) and mother's GDM (OR = 2.184, 95% CI: 1.153-4.134) were high risk factors for neonatal hypoglycemia. The incidence of hypoglycemia in infants was significantly associated with various clinical factors. And monitoring these risk factors is one of important measures to reduce long-term neurological damage caused by neonatal hypoglycemia.

Hyperglycemia and Glucose Variability Are Associated with Worse Brain Function and Seizures in Neonatal Encephalopathy: A Prospective Cohort Study

OBJECTIVES

To investigate how glucose abnormalities correlate with brain function on amplitude-integrated electroencephalography (aEEG) in infants with neonatal encephalopathy.

STUDY DESIGN

Neonates born at full term with encephalopathy were enrolled within 6 hours of birth in a prospective cohort study at a pediatric academic referral hospital. Continuous interstitial glucose monitors and aEEG were placed soon after birth and continued for 3 days. Episodes of hypoglycemia (≤50 mg/dL; ≤2.8 mmol/L) and hyperglycemia (>144 mg/dL; >8.0 mmol/L) were identified. aEEG was classified in 6-hour epochs for 3 domains (background, sleep-wake cycling, electrographic seizures). Generalized estimating equations assessed the relationship of hypo- or hyperglycemia with aEEG findings, adjusting for clinical markers of hypoxia-ischemia (Apgar scores, umbilical artery pH, and base deficit).

RESULTS

Forty-five infants (gestational age 39.5 ± 1.4 weeks) were included (24 males). During aEEG monitoring, 16 episodes of hypoglycemia were detected (9 infants, median duration 77.5, maximum 220 minutes) and 18 episodes of hyperglycemia (13 infants, median duration 237.5, maximum 3125 minutes). Epochs of hypoglycemia were not associated with aEEG changes. Compared with epochs of normoglycemia, epochs of hyperglycemia were associated with worse aEEG background scores (B 1.120, 95% CI 0.501-1.738, P < .001), less sleep-wake cycling (B 0.587, 95% CI 0.417-0.757, P < .001) and more electrographic seizures (B 0.433, 95% CI 0.185-0.681, P = .001), after adjusting for hypoxia-ischemia severity.

CONCLUSIONS

In neonates with encephalopathy, epochs of hyperglycemia were temporally associated with worse global brain function and seizures, even after we adjusted for hypoxia-ischemia severity. Whether hyperglycemia causes neuronal injury or is simply a marker of severe brain injury requires further study.

Factors influencing glycaemic stability after neonatal hypoglycaemia and relationship to neurodevelopmental outcome

Higher and unstable glucose concentrations in the first 48 hours in neonates at risk of hypoglycaemia have been associated with neurosensory impairment. It is unclear what defines and contributes to instability. This was a prospective study of term and late preterm babies (N = 139) born at risk of neonatal hypoglycaemia who had interstitial glucose (IG) monitoring and ≥1 hypoglycaemic episode <48 hours after birth (blood glucose concentration <2.6 mmol/l [<47 mg/dl]). For 6-hour epochs after each hypoglycaemic episode, masked IG parameters (time to reach maximum IG concentration [hours]; range, average, maximum and minimum IG concentrations; proportion of IG measurements outside the central band of 3–4 mmol/l [54–72 md/dl]; and total duration [hours] of IG concentrations <2.6 mmol/l) were analysed in tertiles and related to: (i) glycaemic instability in the first 48 hours (defined as the proportion of blood glucose concentrations outside the central band in the first 48 hours); (ii) risk factors and treatment for each episode; and (iii) risk of neurosensory impairment at 4.5 years, or at 2 years if a child was not seen at 4.5 years. Glycaemic instability in the first 48 hours was related to IG instability after hypoglycaemia. Risk factors for hypoglycaemia were not related to IG parameters. Treatment with intravenous dextrose was associated with higher IG maximum and range, and lower minimum compared to treatment with dextrose gel plus breast milk, breast milk alone or formula alone. The risk of neurosensory impairment was increased with both shorter and longer time to reach maximum epoch IG (P = 0.04; lower tertile [0.4–2.2 hours] vs middle [2.3–4.2 hours] OR 3.10 [95% CI 1.03; 9.38]; higher tertile [4.3–6.0 hours] vs middle OR 3.07; [95% CI 1.01; 9.24]). Glycaemic response to hypoglycaemia contributes to overall glycaemic instability in newborns and is influenced by treatment. Slow or rapid recovery of hypoglycaemia appears to be associated with neurosensory impairment.

Recurrent moderate hypoglycemia exacerbates oxidative damage and neuronal death leading to cognitive dysfunction after the hypoglycemic coma

Moderate recurrent hypoglycemia (RH) is frequent in Type 1 diabetes mellitus (TIDM) patients who are under intensive insulin therapy increasing the risk for severe hypoglycemia (SH). The consequences of RH are not well understood and its repercussions on neuronal damage and cognitive function after a subsequent episode of SH have been poorly investigated. In the current study, we have addressed this question and observed that previous RH during seven consecutive days exacerbated oxidative damage and neuronal death induced by a subsequent episode of SH accompanied by a short period of coma, in the parietal cortex, the striatum and mainly in the hippocampus. These changes correlated with a severe decrease in reduced glutathione content (GSH), and a significant spatial and contextual memory deficit. Administration of the antioxidant, N-acetyl-L-cysteine, (NAC) reduced neuronal death and prevented cognitive impairment. These results demonstrate that previous RH enhances brain vulnerability to acute hypoglycemia and suggests that this effect is mediated by the decline in the antioxidant defense and oxidative damage. The present results highlight the importance of an adequate control of moderate hypoglycemic episodes in TIDM.

Neonatal Hypoglycemia: Is There a Sweet Spot?

Hypoglycemia is one of the most common neonatal problems. Despite increasing evidence that hypoglycemia is linked to neurologic impairment, knowledge regarding the specific value or duration of hypoglycemia that results in injury to the brain remains unclear. Current published statements/guidelines focused on preventing clinically significant hypoglycemia are conflicting and continue to be based on low evidence. This article reviews transitional events leading to extrauterine euglycemia, risk factors contributing to transient or persistent hypoglycemia, and common treatment approaches. Current information related to neurodevelopmental outcomes and screening strategies to prevent significant hypoglycemia with early treatment is described.

Neonatal Glycaemia and Neurodevelopmental Outcomes: A Systematic Review and Meta-Analysis

BACKGROUND

Hypoglycaemia is the most common metabolic problem in neonates but there is no universally accepted threshold for safe blood glucose concentrations due to uncertainty regarding effects on neurodevelopment.

OBJECTIVE

To systematically assess the association between neonatal hypoglycaemia on neurodevelopment outcomes in childhood and adolescence.

METHODS

We searched MEDLINE, EMBASE, CINAHL, and PsycINFO from inception until February 2018. We included studies that reported one or more prespecified outcomes and compared children exposed to neonatal hypoglycaemia with children not exposed. Studies of neonates with congenital malformations, inherited metabolic disorders and congenital hyperinsulinism were excluded. Two authors independently extracted data using a customized form. We used ROBINS-I to assess risk of bias, GRADE for quality of evidence, and REVMAN for meta-analysis (inverse variance, fixed effects).

RESULTS

1,665 studies were screened, 61 reviewed in full, and 11 included (12 publications). In early childhood, exposure to neonatal hypoglycaemia was not associated with neurodevelopmental impairment (n = 1,657 infants; OR = 1.16, 95% CI = 0.86-1.57) but was associated with visual-motor impairment (n = 508; OR = 3.46, 95% CI = 1.13-10.57) and executive dysfunction (n = 463; OR = 2.50, 95% CI = 1.20-5.22). In mid-childhood, neonatal hypoglycaemia was associated with neurodevelopmental impairment (n = 54; OR = 3.62, 95% CI = 1.05-12.42) and low literacy (n = 1,395; OR = 2.04, 95% CI = 1.20-3.47) and numeracy (n = 1,395; OR = 2.04, 95% CI = 1.21-3.44). No data were available for adolescents.

CONCLUSIONS

Neonatal hypoglycaemia may have important long-lasting adverse effects on neurodevelopment that may become apparent at later ages. Carefully designed randomized trials are required to determine the optimal management of neonates at risk of hypoglycaemia with long-term follow-up at least to school age.

Brain-derived neurotrophic factor inhibits hyperglycemia-induced apoptosis and downregulation of synaptic plasticity-related proteins in hippocampal neurons via the PI3K/Akt pathway

It is not known whether brain-derived neurotrophic factor (BDNF) protects hippocampal neurons from high glucose-induced apoptosis and/or synaptic plasticity dysfunction. The present study aimed to assess whether BDNF exerted a neuroprotective effect in rat hippocampal neurons exposed to high glucose and examine the underlying mechanisms. The apoptosis of primary hippocampal neurons was assessed by Annexin V-fluorescein isothiocyanate/propidium iodide staining. The mRNA and protein expression levels were measured by reverse transcription- quantitative polymerase chain reaction and western blot experiments, respectively. Synaptic plasticity was evaluated by the immunolocalization of synaptophysin (Syn). Exposure of the hippocampal neurons to high glucose (75 mM for 72 h) resulted in cell apoptosis, decreased mRNA and protein expression levels of three synaptic plasticity-related proteins (Syn, Arc and cyclic AMP response element-binding protein), and changes in the cellular distribution of Syn, indicating loss of synaptic density. These effects of high glucose were partially or completely reversed by prior administration of BDNF (50 ng/ml for 24 h). Pre-treatment with wortmannin, a phosphatidylinositol-3-kinase (PI3K) inhibitor, suppressed the ability of BDNF to inhibit the effects of high glucose. In addition, BDNF significantly upregulated the tropomyosin-related kinase B, its cognate receptor, Akt and phosphorylated Akt at the protein levels under high glucose conditions. In conclusion, high glucose induced apoptosis and downregulated synaptic plasticity-related proteins in hippocampal neurons. These effects were reversed by BDNF via the PI3K/Akt signaling pathway.

Neonatal hyperglycemia alters the neurochemical profile, dendritic arborization and gene expression in the developing rat hippocampus

Hyperglycemia (blood glucose concentration >150 mg/dL) is common in extremely low gestational age newborns (ELGANs; birth at <28 week gestation). Hyperglycemia increases the risk of brain injury in the neonatal period. The long-term effects are not well understood. In adult rats, hyperglycemia alters hippocampal energy metabolism. The effects of hyperglycemia on the developing hippocampus were studied in rat pups. In Experiment 1, recurrent hyperglycemia of graded severity (moderate hyperglycemia (moderate-HG), mean blood glucose 214.6 ± 11.6 mg/dL; severe hyperglycemia (severe-HG), 338.9 ± 21.7 mg/dL; control, 137.7 ± 2.6 mg/dL) was induced from postnatal day (P) 3 to P12. On P30, the hippocampal neurochemical profile was determined using in vivo ¹ H MR spectroscopy. Dendritic arborization in the hippocampal CA1 region was determined using microtubule-associated protein (MAP)-2 immunohistochemistry. In Experiment 2, continuous hyperglycemia (mean blood glucose 275.3 ± 25.8 mg/dL; control, 142.3 ± 2.6 mg/dL) was induced from P2 to P6 by injecting streptozotocin (STZ) on P2. The mRNA expression of glycogen synthase 1 (Gys1), lactate dehydrogenase (Ldh), glucose transporters 1 (Glut1) and 3 (Glut3) and monocarboxylate transporters 1 (Mct1), 2 (Mct2) and 4 (Mct4) in the hippocampus was determined on P6. In Experiment 1, MRS demonstrated lower lactate concentration and glutamate/glutamine (Glu/Gln) ratio in the severe-HG group, compared with the control group (p < 0.05). Phosphocreatine/creatine ratio was higher in both hyperglycemia groups (p < 0.05). MAP-2 histochemistry demonstrated longer apical segment length, indicating abnormal synaptic efficacy in both hyperglycemia groups (p < 0.05). Experiment 2 showed lower Glut1, Gys1 and Mct4 expression and higher Mct1 expression in the hyperglycemia group, relative to the control group (p < 0.05). These results suggest that hyperglycemia alters substrate transport, lactate homeostasis, dendritogenesis and Glu-Gln cycling in the developing hippocampus. Abnormal neurochemical profile and dendritic structure due to hyperglycemia may partially explain the long-term hippocampus-mediated cognitive deficits in human ELGANs.

Hypoglycemia: When to Treat?

Hypoglycemia is the most common metabolic disorder encountered in neonates. The definition of hypoglycemia as well as its clinical significance and management remain controversial. Most cases of neonatal hypoglycemia are transient, respond readily to treatment, and are associated with an excellent prognosis. Persistent hypoglycemia is more likely to be associated with abnormal endocrine conditions, such as hyperinsulinemia, as well as possible neurologic sequelae. Manifestations of hypoglycemia include seizures which can result in noteworthy neuromorbidity in the long haul. Thus, hypoglycemia constitutes a neonatal emergency which requires earnest analytic assessment and prompt treatment. In this review, we have tried to cover the pathophysiology, the screening protocol for high-risk babies, management, long-term neurologic sequelae associated with neonatal hypoglycemia, with evidence-based answers wherever possible, and our own practices.

Continuous glucose monitoring in neonates: a review

Continuous glucose monitoring (CGM) is well established in the management of diabetes mellitus, but its role in neonatal glycaemic control is less clear. CGM has provided important insights about neonatal glucose metabolism, and there is increasing interest in its clinical use, particularly in preterm neonates and in those in whom glucose control is difficult. Neonatal glucose instability, including hypoglycaemia and hyperglycaemia, has been associated with poorer neurodevelopment, and CGM offers the possibility of adjusting treatment in real time to account for individual metabolic requirements while reducing the number of blood tests required, potentially improving long-term outcomes. However, current devices are optimised for use at relatively high glucose concentrations, and several technical issues need to be resolved before real-time CGM can be recommended for routine neonatal care. These include: 1) limited point accuracy, especially at low or rapidly changing glucose concentrations; 2) calibration methods that are designed for higher glucose concentrations of children and adults, and not for neonates; 3) sensor drift, which is under-recognised; and 4) the need for dynamic and integrated metrics that can be related to long-term neurodevelopmental outcomes. CGM remains an important tool for retrospective investigation of neonatal glycaemia and the effect of different treatments on glucose metabolism. However, at present CGM should be limited to research studies, and should only be introduced into routine clinical care once benefit is demonstrated in randomised trials.

Association of Neonatal Glycemia With Neurodevelopmental Outcomes at 4.5 Years

IMPORTANCE

Hypoglycemia is common during neonatal transition and may cause permanent neurological impairment, but optimal intervention thresholds are unknown.

OBJECTIVE

To test the hypothesis that neurodevelopment at 4.5 years is related to the severity and frequency of neonatal hypoglycemia.

DESIGN, SETTING, AND PARTICIPANTS

The Children With Hypoglycemia and Their Later Development (CHYLD) Study is a prospective cohort investigation of moderate to late preterm and term infants born at risk of hypoglycemia. Clinicians were masked to neonatal interstitial glucose concentrations; outcome assessors were masked to neonatal glycemic status. The setting was a regional perinatal center in Hamilton, New Zealand. The study was conducted from December 2006 to November 2010. The dates of the follow-up were September 2011 to June 2015. Participants were 614 neonates born from 32 weeks' gestation with at least 1 risk factor for hypoglycemia, including diabetic mother, preterm, small, large, or acute illness. Blood and masked interstitial glucose concentrations were measured for up to 7 days after birth. Infants with hypoglycemia (whole-blood glucose concentration <47 mg/dL) were treated to maintain blood glucose concentration of at least 47 mg/dL.

EXPOSURES

Neonatal hypoglycemic episode, defined as at least 1 consecutive blood glucose concentration less than 47 mg/dL, a severe episode (<36 mg/dL), or recurrent (≥3 episodes). An interstitial episode was defined as an interstitial glucose concentration less than 47 mg/dL for at least 10 minutes.

MAIN OUTCOMES AND MEASURES

Cognitive function, executive function, visual function, and motor function were assessed at 4.5 years. The primary outcome was neurosensory impairment, defined as poor performance in one or more domains.

RESULTS

In total, 477 of 604 eligible children (79.0%) were assessed. Their mean (SD) age at the time of assessment was 4.5 (0.1) years, and 228 (47.8%) were female. Those exposed to neonatal hypoglycemia (280 [58.7%]) did not have increased risk of neurosensory impairment (risk difference [RD], 0.01; 95% CI, -0.07 to 0.10 and risk ratio [RR], 0.96; 95% CI, 0.77 to 1.21). However, hypoglycemia was associated with increased risk of low executive function (RD, 0.05; 95% CI, 0.01 to 0.10 and RR, 2.32; 95% CI, 1.17 to 4.59) and visual motor function (RD, 0.03; 95% CI, 0.01 to 0.06 and RR, 3.67; 95% CI, 1.15 to 11.69), with highest risk in children exposed to severe, recurrent, or clinically undetected (interstitial episodes only) hypoglycemia.

CONCLUSIONS AND RELEVANCE

Neonatal hypoglycemia was not associated with increased risk of combined neurosensory impairment at 4.5 years but was associated with a dose-dependent increased risk of poor executive function and visual motor function, even if not detected clinically, and may thus influence later learning. Randomized trials are needed to determine optimal screening and intervention thresholds based on assessment of neurodevelopment at least to school age.

Characterization of the concurrent metabolic changes in brain and plasma during insulin-induced moderate hypoglycemia using 1H NMR spectroscopy in juvenile rats

Treatment of hypoglycemia in children is currently based on plasma glucose measurements. This approach may not ensure neuroprotection since plasma glucose does not reflect the dynamic state of cerebral energy metabolism. To determine whether cerebral metabolic changes during hypoglycemia could be better characterized using plasma metabolomic analysis, insulin-induced acute hypoglycemia was induced in 4-week-old rats. Brain tissue and concurrent plasma samples were collected from hypoglycemic (N=7) and control (N=7) rats after focused microwave fixation to prevent post-mortem metabolic changes. The concentration of 29 metabolites in brain and 34 metabolites in plasma were determined using ¹H NMR spectroscopy at 700MHz and examined using partial least squares-discriminant analysis. The sensitivity of plasma glucose for detecting cerebral energy failure was assessed by determining its relationship to brain phosphocreatine. The brain and plasma metabolite profiles of the hypoglycemia group were distinct from the control group (brain: R²=0.92, Q²=0.31; plasma: R²=0.95, Q²=0.74). Concentration differences in glucose, ketone bodies and amino acids were responsible for the intergroup separation. There was 45% concordance between the brain and plasma metabolite profiles. Brain phosphocreatine correlated with brain glucose (control group: R²=0.86; hypoglycemia group: R²=0.59; p<0.05), but not with plasma glucose. The results confirm that plasma glucose is an insensitive biomarker of cerebral energy changes during hypoglycemia and suggest that a plasma metabolite profile is superior for monitoring cerebral metabolism.

Oral Dextrose Gel Reduces the Need for Intravenous Dextrose Therapy in Neonatal Hypoglycemia

BACKGROUND

Newborn infants with risk factors may require intravenous (IV) dextrose for asymptomatic hypoglycemia. Administration of IV dextrose and transfer to the neonatal intensive care unit (NICU) may interfere with parent-infant bonding.

OBJECTIVE

To study the effect of implementing dextrose gel supplement with feeds in late preterm/term infants affected by asymptomatic hypoglycemia on reducing IV dextrose therapy.

METHOD

A retrospective study was conducted before and after dextrose gel use: 05/01/2014 to 10/31/2014 and 11/01/2014 to 04/30/2015, respectively. Asymptomatic hypoglycemic (blood glucose level <45 mg/dl) infants in the newborn nursery (NBN) were given a maximum of 3 doses of dextrose gel (200 mg/kg of 40% dextrose) along with feeds. Transfer to the NICU for IV dextrose was considered treatment failure.

RESULTS

Dextrose gel with feeds increased the blood glucose level in 184/250 (74%) of asymptomatic hypoglycemic infants compared to 144/248 (58%) with feeds only (p < 0.01). Transfer from the NBN to the NICU for IV dextrose decreased from 35/1,000 to 25/1,000 live births (p < 0.01). Exclusive breastfeeding improved from 19 to 28% (p = 0.03).

CONCLUSIONS

Use of dextrose gel with feeds reduced the need for IV fluids, avoided separation from the mother and promoted breastfeeding. Neonates who failed dextrose gel therapy were more likely to be large for gestational age, delivered by cesarean section and had lower baseline blood glucose levels.

Recurrent Moderate Hypoglycemia Suppresses Brain-Derived Neurotrophic Factor Expression in the Prefrontal Cortex and Impairs Sensorimotor Gating in the Posthypoglycemic Period in Young Rats

Recurrent hypoglycemia is common in infants and children. In developing rat models, recurrent moderate hypoglycemia leads to neuronal injury in the medial prefrontal cortex. To understand the effects beyond neuronal injury, 3-week-old male rats were subjected to 5 episodes of moderate hypoglycemia (blood glucose concentration, approx. 30 mg/dl for 90 min) once daily from postnatal day 24 to 28. Neuronal injury was determined using Fluoro-Jade B histochemistry on postnatal day 29. The effects on brain-derived neurotrophic factor (BDNF) and its cognate receptor, tyrosine kinase receptor B (TrkB) expression, which is critical for prefrontal cortex development, were determined on postnatal day 29 and at adulthood. The effects on prefrontal cortex-mediated function were determined by assessing the prepulse inhibition of the acoustic startle reflex on postnatal day 29 and 2 weeks later, and by testing for fear-potentiated startle at adulthood. Recurrent hypoglycemia led to neuronal injury confined primarily to the medial prefrontal cortex. BDNF/TrkB expression in the prefrontal cortex was suppressed on postnatal day 29 and was accompanied by lower prepulse inhibition, suggesting impaired sensorimotor gating. Following the cessation of recurrent hypoglycemia, the prepulse inhibition had recovered at 2 weeks. BDNF/TrkB expression in the prefrontal cortex had normalized and fear-potentiated startle was intact at adulthood. Recurrent moderate hypoglycemia during development has significant adverse effects on the prefrontal cortex in the posthypoglycemic period.

Neonatal Glycemia and Neurodevelopmental Outcomes at 2 Years

BACKGROUND

Neonatal hypoglycemia is common and can cause neurologic impairment, but evidence supporting thresholds for intervention is limited.

METHODS

We performed a prospective cohort study involving 528 neonates with a gestational age of at least 35 weeks who were considered to be at risk for hypoglycemia; all were treated to maintain a blood glucose concentration of at least 47 mg per deciliter (2.6 mmol per liter). We intermittently measured blood glucose for up to 7 days. We continuously monitored interstitial glucose concentrations, which were masked to clinical staff. Assessment at 2 years included Bayley Scales of Infant Development III and tests of executive and visual function.

RESULTS

Of 614 children, 528 were eligible, and 404 (77% of eligible children) were assessed; 216 children (53%) had neonatal hypoglycemia (blood glucose concentration, <47 mg per deciliter). Hypoglycemia, when treated to maintain a blood glucose concentration of at least 47 mg per deciliter, was not associated with an increased risk of the primary outcomes of neurosensory impairment (risk ratio, 0.95; 95% confidence interval [CI], 0.75 to 1.20; P=0.67) and processing difficulty, defined as an executive-function score or motion coherence threshold that was more than 1.5 SD from the mean (risk ratio, 0.92; 95% CI, 0.56 to 1.51; P=0.74). Risks were not increased among children with unrecognized hypoglycemia (a low interstitial glucose concentration only). The lowest blood glucose concentration, number of hypoglycemic episodes and events, and negative interstitial increment (area above the interstitial glucose concentration curve and below 47 mg per deciliter) also did not predict the outcome.

CONCLUSIONS

In this cohort, neonatal hypoglycemia was not associated with an adverse neurologic outcome when treatment was provided to maintain a blood glucose concentration of at least 47 mg per deciliter. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and others.).

Hypothalamic-Pituitary-Adrenal Axis Programming after Recurrent Hypoglycemia during Development

Permanent brain injury is a complication of recurrent hypoglycemia during development. Recurrent hypoglycemia also has adverse consequences on the neuroendocrine system. Hypoglycemia-associated autonomic failure, characterized by ineffective glucose counterregulation during hypoglycemia, is well described in children and adults on insulin therapy for diabetes mellitus. Whether recurrent hypoglycemia also has a programming effect on the hypothalamus-pituitary-adrenal cortex (HPA) axis has not been well studied. Hypoglycemia is a potent stress that leads to increased glucocorticoid secretion in all age groups, including the perinatal period. Other conditions associated with exposure to excess glucocorticoid in the perinatal period have a programming effect on the HPA axis activity. Limited animal data suggest the possibility of similar programming effect after recurrent hypoglycemia in the postnatal period. The age at exposure to hypoglycemia likely determines the HPA axis response in adulthood. Recurrent hypoglycemia in the early postnatal period likely leads to a hyperresponsive HPA axis, whereas recurrent hypoglycemia in the late postnatal period lead to a hyporesponsive HPA axis in adulthood. The age-specific programming effects may determine the neuroendocrine response during hypoglycemia and other stressful events in individuals with history of recurrent hypoglycemia during development.

β-Hydroxybutyrate attenuates NMDA-induced spasms in rats with evidence of neuronal stabilization on MR spectroscopy

BACKGROUND

Infantile spasms (IS) is a devastating epileptic encephalopathy. The ketogenic diet (KD) has been successfully used as a treatment for IS. This study was designed to test whether beta-hydroxybutyrate (BHB), a major metabolite of the KD, is effective in an animal model of IS.

METHODS

Pregnant rats received betamethasone on gestational day 15. The offspring received either single [30min prior to NMDA-triggered spasms on postnatal day (P) 15] or prolonged (three per day from P12 to P15) i.p. BHB. An additional experiment used repeated bouts of spasms on P12, P13, and P15 with randomized prolonged BHB treatment initiated after the first spasms. We determined the latency to onset of spasms and the number of spasms after the NMDA injection on P15. The rats that received randomized BHB treatment were also monitored with open field, sociability, and fear-conditioning tests and underwent in vivo (1)H MR imaging on a 9.4T MR system after NMDA-induced spasms. The acquired (1)H MR spectra were quantified using LC model.

RESULTS

Single-dose BHB pretreatment had no effect on spasms. In contrast, prolonged pretreatment with BHB significantly delayed the onset and decreased the frequency of spasms. In addition, randomized prolonged BHB treatment resulted in a significant reduction in number of spasms at P15. BHB treatment had no significant effect on motor activities, but significantly decreased the interactions with strangers and increased the contextual memory. On MR spectroscopic analysis of randomized prolonged BHB-treated rats at 24h after the cluster of spasms, the elevation of GABA, glutamine, glutamate, total creatine, macromolecule-plus lipids, and N-acetylaspartate levels after spasms were significantly attenuated by randomized BHB treatment (p<0.05).

SIGNIFICANCE

Prolonged administration of BHB directly suppresses development of spasms in a rat model of IS with acute stabilization of brain metabolites. Additionally, BHB appears to decrease the interests to other rats and improve memory responses.