Standardised practices in the networked management of congenital hyperinsulinism: a UK national collaborative consensus

Comprehensive clinical and molecular characterization with long-term outcomes in 40 patients with congenital hyperinsulinism

PURPOSE

Congenital hyperinsulinism (CHI) represents the most frequent cause of recurrent hypoglycemia in neonates and infants, stemming from defects in the regulatory pathways of insulin secretion from pancreatic beta cells. This study aims to assess the clinical and genetic characteristics of a CHI cohort and to discuss the complexities involved in managing this heterogeneous disorder.

METHODS

Forty patients (23 girls) with CHI were included in the study. Data on the diagnosis and treatment of CHI were obtained from the medical records.

RESULTS

The median age at diagnosis was 1.4 months (range 0.1-30 months). The mean gestational age was 37.8 ± 2.4 weeks, and the birth weight was 1.1 ± 2.0 SDS. The consanguinity ratio was 35.0%. Median glucose, insulin, and C-peptide concentrations at diagnosis were 34.0 mg/dl (IQR 25.2-41.7), 12.4µU/ml (IQR 4.4-27.1), and 1.5 ng/ml (IQR 0.7-3.8), respectively. Molecular genetic diagnosis could be established in 62.5% (n = 25). Pathogenic variants were predominantly identified in the KATP channel genes (17/25, 68%), with the ABCC8 being the most frequent (n = 15; biallelic: 8, monoallelic: 7). KCNJ11 variants were identified in two (5.0%), GLUD1 variants in three (7.5%), and HADH variants in five patients (12.5%). Pancreatectomy was performed in 10 patients, with a mean age at the time of surgery of 3.9 ± 3.2 months. The genetic etiology was identified in all patients who underwent pancreatectomy, all of whom had defects in the KATP channel. ABCC8 variants were detected in nine (biallelic: 5, monoallelic: 4), while a biallelic variant in the KCNJ11 was identified in one case.

CONCLUSION

A molecular genetic diagnosis was identified in approximately two-thirds of our cohort, underscoring the significance of genetic testing in the management of CHI. Ongoing advances in genetic technologies are anticipated to enhance our understanding of the etiopathogenesis of CHI and support the development of more personalized therapeutic strategies. Although the genotype-phenotype correlation remains only partially elucidated, specific genetic variants may provide predictive insights into treatment resistance, thereby informing more targeted treatment approaches.

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.

Reassessing Pancreatectomy in Diffuse Congenital Hyperinsulinism: A Tale of 2 Brothers With Homozygous KCNJ11 Variants

Congenital hyperinsulinism (CHI) is a rare but serious disorder characterized by a dysregulated increase in insulin secretion, leading to hypoglycemia. Existing literature on CHI highlights the importance of early recognition and maintenance of blood glucose levels, due to the risk of neurological damage posed by uncorrected hypoglycemia. The cases presented highlight the treatment of 2 brothers who developed neonatal hypoglycemia due to diffuse CHI resulting from homozygous KCNJ11 variants. These cases demonstrate the challenges in maintaining normoglycemia in cases of CHI through medical and surgical therapies. The older sibling, Brother 1, underwent pharmacological treatment and a near-total pancreatectomy at 2.5 months. The outcomes of his treatment highlight the limitations of pancreatectomy in the management of diffuse CHI, as he experienced challenges such as continued hypoglycemic episodes and eventual development of diabetes. Brother 2 was managed with pharmacological therapies and a long-term feeding regimen via gastrostomy. At 6 years he was able to maintain normoglycemia with weaning of octreotide therapy. This paper contributes to our understanding of how to best manage diffuse CHI by emphasizing the limitations and adverse long-term outcomes of pancreatectomy-namely ongoing hypoglycemia and development of diabetes and pancreatic exocrine insufficiency.

Biomarkers and Diagnostic Thresholds for Congenital Hyperinsulinism

CONTEXT

Congenital Hyperinsulinism (CHI) is associated with inappropriately high levels of C-peptide in the context of hypoglycemia.

OBJECTIVE

We aimed to better clarify a diagnostic threshold value of C-peptide for children presenting with CHI.

DESIGN

This was a retrospective case-control analysis, examining all hypoglycemia screens, undertaken between 2009 and 2019 at a quaternary paediatrics unit. Plasma C-peptide, insulin, free fatty acid (FFA) and B-hydroxybutyrate (BHOB) concentrations in children diagnosed with CHI were compared with concentrations in children diagnosed with other conditions.

PATIENTS

All patients requiring hypoglycaemic screens at the quaternary children's hospital were analysed.

RESULTS

Median [C-peptide] were statistically significantly different between CHI (147) and non-CHI (72) patients, p < 0.05. The Youden Index indicated that a [C-peptide] value of 291.5 pmol/L would give the greatest optimization of sensitivity (82%) and specificity (99%) for detecting CHI. Median [insulin] differed significantly between the cohorts with a level of 64 pmol/L for CHI patients compared with 0 pmol/L with non-CHI patients (p < 0.01). Median [BOHB] was 0 μmol/L in CHI patients as compared with 2378 μmol/L for non-CHI patients (p < 0.01). Median [FFA] levels were 1910 μmol/L in the non-CHI cohort, compared with 0 in the CHI cohort (p < 0.01).

CONCLUSIONS

This study suggests that a C-peptide concentration greater than 291.5 pmol/L is diagnostic of CHI in children. C-peptide appears to offer the greatest utility as a biochemical diagnostic test for CHI and could be prioritised for laboratory analysis.

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.

First Accuracy and User-Experience Evaluation of New Continuous Glucose Monitoring System for Hypoglycemia Due to Hyperinsulinism

INTRODUCTION

Patients with congenital hyperinsulinism (HI) require constant glucose monitoring to detect and treat recurrent and severe hypoglycemia. Historically, this has been achieved with intermittent self-monitoring blood glucose (SMBG), but patients are increasingly using continuous glucose monitoring (CGM). Given the rapidity of CGM device development, and increasing calls for CGM use from HI families, it is vital that new devices are evaluated early.

METHODS

We provided two months of supplies for the new Dexcom G7 CGM device to 10 patients with HI who had recently finished using the Dexcom G6. Self-monitoring blood glucose was performed concurrently with paired readings providing accuracy calculations. Patients and families completed questionnaires about device use at the end of the two-month study period.

RESULTS

Compared to the G6, the G7 showed a significant reduction in mean absolute relative difference (25%-18%, P < .001) and in the over-read error (Bland Altman +1.96 SD; 3.54 mmol/L to 2.95 mmol/L). This resulted in an improvement in hypoglycemia detection from 42% to 62% (P < .001). Families reported an overall preference for the G7 but highlighted concerns about high sensor failure rates.

DISCUSSION

The reduction in mean absolute relative difference and over-read error and the improvement in hypoglycemia detection implies that the G7 is a safer and more useful device in the management of hypoglycemia for patients with HI. Accuracy, while improved from previous devices, remains suboptimal with 40% of hypoglycemia episodes not detected.

Brain magnetic resonance imaging review suggests unrecognised hypoglycaemia in childhood

Introduction

Neonatal and early-life hypoglycaemia, is a frequent finding but is often non-specific and asymptomatic, making detection and diagnosis challenging. Hypoglycaemia-induced cerebral injury can be identified by magnetic resonance imaging (MRI) changes in cerebral white matter, occipital lobes, and posterior parietotemporal regions. It is unknown if children may have hypoglycaemic brain injury secondary to unrecognised hypoglycaemia in early life. We have examined retrospective radiological findings of likely brain injury by neuroimaging to investigate the existence of previous missed hypoglycaemic events.

Methods

Retrospective MRI data in children in a single tertiary centre, over a ten-year period was reviewed to identify potential cases of unrecognised early-life hypoglycaemia. A detailed search from an electronic radiology repository involved the term "hypoglycaemia'' from text-based reports. The initial report was used for those who required serial scanning. Images specific to relevant reports were further reviewed by a designated paediatric neuroradiologist to confirm likely hypoglycaemia induced brain injury. Medical records of those children were subsequently reviewed to assess if the hypoglycaemia had been diagnosed prior to imaging.

Results

A total of 107 MR imaging reports were identified for review, and 52 (48.5%) showed typical features strongly suggestive of hypoglycaemic brain injury. Medical note review confirmed no documented clinical information of hypoglycaemia prior to imaging in 22 (42%) patients, raising the likelihood of missed hypoglycaemic events resulting in brain injury.

Conclusions

We have identified the existence of unrecognised childhood hypoglycaemia through neuroimaging review. This study highlights the need for heightened awareness of early life hypoglycaemia to prevent adverse neurological outcomes later in childhood.