Clinical practice guidelines for congenital hyperinsulinism

A case of congenital hyperinsulinism presenting with diabetes after long-term diazoxide therapy

Congenital hyperinsulinism (CHI) is the most common form of persistent hypoglycemia in infants, and diazoxide is the most widely used drug for its treatment. Diazoxide suppresses insulin secretion and attenuates hypoglycemia by binding to sulfonylurea receptor 1 and activating KATP channels. While the short-term side effects of this drug, such as edema and blood cell abnormalities, are well known, the clinical course after its long-term oral administration remains unclear. Furthermore, there are currently no case reports clearly demonstrating a causal relationship between diazoxide and impaired glucose tolerance. We herein describe the case of a 9-year-old girl with CHI complicated with Kabuki syndrome who presented with impaired glucose tolerance due to decreased initial insulin secretion and insulin resistance caused by obesity resulting from diazoxide medication. This is a rare case of the insufficient effects of insulin due to the oral administration of diazoxide, and provides insights for managing the long-term administration of diazoxide to children.

Case report: Exceptional transmission of congenital hyperinsulinism from a focal CHI mother to her diffuse CHI dichorionic diamniotic twins

We present the case of a 36-year-old female who was diagnosed at birth with CHI that caused severe hypoglycaemia unresponsive to Diazoxide. Subtotal pancreatectomy was performed at the age of three weeks. Later, histological analysis of her pancreas in a research setting revealed a focal form of CHI. Genetic testing was not available at that time. The patient developed pancreatic exocrine deficiency and insulin-dependent diabetes at the age of 9 years. In 2016, a genetic test revealed a missense heterozygous variant in the ABCC8 gene inherited from her father and classified as having a recessive inheritance. The geneticist concluded that the risk of CHI for her offspring would be low (1/600), making pregnancy favourable. As there was no consanguinity in the family, testing the future father was deemed unnecessary (carrier frequency 1/150 in the general population). The pregnancy occurred spontaneously in 2020 and at a gestational age of 28 weeks, the mother went into premature labour. An emergency C-section was performed in April 2021 resulting in the birth of bichorial bi-amniotic male twins. Following birth, both newborns experienced persistent severe hypoglycaemia which required glucagon treatment and intravenous glucose infusion initially, followed by Diazoxide from day 51 after birth, without satisfactory response. Continuous intravenous Octreotide treatment was introduced on day 72. Due to the recurrence of hypoglycaemia episodes despite reaching maximum doses of Octreotide, from day 92 the treatment was switched to Pasireotide. Genetic tests revealed the same genotypes for both infants: the exon 39 missense variant (c.4716C>A; p.Ser1572Arg) inherited from their mother and a truncating variant in exon 28 (c.3550del; p.Val1184*), inherited from their asymptomatic father. As a result of inheriting two recessive variants of the ABCC8 gene, the children were diagnosed with a diffuse form of CHI, consistent with the diazoxide-unresponsive presentation. This situation is very rare outside consanguinity. This case emphasises the significance of genetic counselling for individuals with a history of rare diseases outside the context of consanguinity, as there is a potential risk of recurrence. Prenatal diagnosis can lead to better outcomes for affected neonates, as well as help families make informed decisions about future pregnancies.

Clinical management of diazoxide-unresponsive congenital hyperinsulinism: A single-center experience

The most common cause of persistent hypoglycemia in newborns and children is congenital hyperinsulinism (CHI). Remarkable advancements in diagnostic tools and treatments, including novel imaging and genetic techniques, and continuous subcutaneous octreotide administration, have improved the prognosis of diazoxide-unresponsive CHI; however, in clinical practice, some issues remain. Here, we report a case series consisting of four adenosine triphosphate-sensitive potassium-associated CHI cases, discuss the practical use of new international guidelines published in 2023, and suggest clinical issues associated with CHI management. Based on the clinical experience of two diffuse and two focal CHI cases, we employed an updated treatment strategy, including genetic diagnosis to determine treatment plans, careful catheter management, switching from octreotide to long-acting somatostatin, effective utilization of a continuous glucose monitoring (CGM) device, measures for feeding problems, and individualized and systematic developmental follow-up. Particularly, our cases suggest a safe method of switching from octreotide to lanreotide, elucidate the efficacy of home-based CGM monitoring, and indicate need for personalized support for feeding problems. Severe CHI is a rare and challenging disorder; thus, further accumulation of experience according to new treatment strategies is essential in generating high-quality evidence for the development and approval of new treatment options.

A case of diffuse congenital hyperinsulinism in which continuous glucose monitoring contributed to the choice of a treatment strategy following a subtotal pancreatectomy

Patients with diffuse congenital hyperinsulinism (CHI) refractory to drug therapy require subtotal or near-total pancreatectomy. Although almost all patients develop diabetes postoperatively, the clinical course and timing of insulin therapy remain unclear. A 7-yr-old girl presented with recurrent hypoglycemia shortly after birth and a relatively elevated insulin level, which confirmed the diagnosis of CHI. Genetic analysis revealed compound heterozygous ATP-binding cassette, Subfamily C, Member 8 pathogenic variants and diffuse CHI was suspected. Because her condition was refractory to diazoxide and octreotide, she underwent a subtotal pancreatectomy at the age of 4 mo. The drug therapy was discontinued. Although an oral glucose tolerance test at the age of 2 yr showed hyperglycemia after loading, continuous glucose monitoring (CGM) revealed that her daily glucose trends were almost within the 70-180 mg/dL range, and mild hypoglycemia appeared during the daytime. After the age of 6 yr, CGM showed an elevation in glucose trends from midnight to early morning, suggesting that insulin secretion was attenuated and hepatic glucose production was insufficiently suppressed. Insulin therapy was initiated at the age of 7 yr. These results indicate that CGM can be useful for making treatment decisions.

Variability in Diagnosis and Management of Hypoglycemia in Neonatal Intensive Care Unit

OBJECTIVE

 Hypoglycemia, the most common metabolic derangement in the newborn period remains a contentious issue, not only due to various numerical definitions, but also due to limited therapeutical options which either lack evidence to support their efficacy or are increasingly recognized to lead to adverse reactions in this population. This study aimed to investigate neonatologists' current attitudes in diagnosing and managing transient and persistent hypoglycemia in newborns admitted to the Neonatal Intensive Care Unit (NICU).

METHODS

 A web-based electronic survey which included 34 questions and a clinical vignette was sent to U.S. neonatologists.

RESULTS

 There were 246 survey responses with most respondents using local protocols to manage this condition. The median glucose value used as the numerical definition of hypoglycemia in first 48 hours of life (HOL) for symptomatic and asymptomatic term infants and preterm infants was 45 mg/dL (2.5 mmol/L; 25-60 mg/dL; 1.4-3.3 mmol/L), while after 48 HOL the median value was 50 mg/dL (2.8 mmol/L; 30-70 mg/dL; 1.7-3.9 mmol/L). There were various approaches used to manage transient and persistent hypoglycemia that included dextrose gel, increasing caloric content of the feeds using milk fortifiers, using continuous feedings, formula or complex carbohydrates, and use of various medications such as diazoxide, glucocorticoids, and glucagon.

CONCLUSION

 There is still large variability in current practices related to hypoglycemia. Further research is needed not only to provide evidence to support the values used as a numerical definition for hypoglycemia, but also on the efficacy of current strategies used to manage this condition.

KEY POINTS

· Numerical definition of glucose remains variable.. · Strategies managing transient and persistent hypoglycemia are diverse.. · There is a need for further research to investigate efficacy of various treatment options..

Congenital hyperinsulinism and surgical outcome in a single tertiary center in Brazil

OBJECTIVE

Congenital hyperinsulinism (CHI) is a heterogeneous genetic disease characterized by increased insulin secretion and causes persistent hypoglycemia in neonates and infants due to dysregulation of insulin secretion by pancreatic β cells. Babies with severe hypoglycemia and for whom medical treatment has been ineffective usually require surgical treatment with near-total pancreatectomy. To evaluate the clinical and surgical aspects affecting survival outcomes in babies diagnosed with CHI in a single tertiary care center.

METHODS

Retrospective Cohort study involving a single university tertiary center for the treatment of CHI. The authors study the demographics, clinical, laboratory, and surgical outcomes of this casuistic.

RESULTS

61 % were female, 39 % male, Birth weight: 3576 g (±313); Age of onset of symptoms: from the 2nd hour of life to 28 days; Time between diagnosis and surgery ranged between 10 and 60 days; Medical clinical treatment, all patients received glucose solution with a continuous glucose infusion and diazoxide. 81 % of the patients used corticosteroids, 77 %. thiazide, 72 % octreotide, 27 % nifedipine; Neurological sequelae during development and growth: 54 % had some degree of delay in neuropsychomotor development, 27 % obesity. Surgery was performed open in 6 and 12 minimally invasive surgery (MIS).

HISTOPATHOLOGY

2 focal and 16 diffuse, Length of stay (days) was lower in MIS (p < 0.05). Survival was 100 %.

CONCLUSIONS

CHI is a rare and difficult-to-manage tumor that must be performed in a multidisciplinary and tertiary center. Most surgical results are good and the laparoscopic approach to disease has been the best choice for patients.

Adjustment of octreotide dose given via insulin pump based on continuous glucose monitoring (CGM) in a child with congenital hyperinsulinism

OBJECTIVES

CHI is a relevant cause of persistent and severe hypoglycemia and the ABCC8 gene mutation is one of most common cause of the disease. Two main types of CHI have been described, diffuse and focal form. Octreotide is a medication utilized in case of diazoxide-unresponsive forms of CHI. For those CHI focal forms where is decided either to manage medically or until resolutive surgery is completed, octreotide can be administered as subcutaneous injection or as continuous subcutaneous infusion via insulin pump. However, it is unclear how to adjust the drug's daily basal pattern when a pump is used.

CASE PRESENTATION

We present a case of an infant with a diazoxide-unresponsive focal form of CHI, due to ABCC8 mutation ABCC8, treated with octreotide. To better evaluate the glycemic trend, a CGM was placed. In order to achieve a better personalization of the therapy we utilized an insulin pump for octreotide administration.

CONCLUSIONS

The adoption of the CGM and insulin pump, allowed a better personalization of the therapy and a reduction of acute carbohydrate intake, promoting a good auxological growth before resolutive surgery. What is new? Octreotide administered with an insulin pump in patient with CHI allows a wide modulation of the daily therapy. The CGM allows a continuous and a less painful control of the glycemic trend in a patient with CHI. Different basal rates, given via insulin pump may allow a better personalization of the therapy. Prevention of hypoglycemia reduces the acute introduction of carbohydrates, promoting normal growth..

International Guidelines for the Diagnosis and Management of Hyperinsulinism

BACKGROUND

Hyperinsulinism (HI) due to dysregulation of pancreatic beta-cell insulin secretion is the most common and most severe cause of persistent hypoglycemia in infants and children. In the 65 years since HI in children was first described, there has been a dramatic advancement in the diagnostic tools available, including new genetic techniques and novel radiologic imaging for focal HI; however, there have been almost no new therapeutic modalities since the development of diazoxide.

SUMMARY

Recent advances in neonatal research and genetics have improved our understanding of the pathophysiology of both transient and persistent forms of neonatal hyperinsulinism. Rapid turnaround of genetic test results combined with advanced radiologic imaging can permit identification and localization of surgically-curable focal lesions in a large proportion of children with congenital forms of HI, but are only available in certain centers in "developed" countries. Diazoxide, the only drug currently approved for treating HI, was recently designated as an "essential medicine" by the World Health Organization but has been approved in only 16% of Latin American countries and remains unavailable in many under-developed areas of the world. Novel treatments for HI are emerging, but they await completion of safety and efficacy trials before being considered for clinical use.

KEY MESSAGES

This international consensus statement on diagnosis and management of HI was developed in order to assist specialists, general pediatricians, and neonatologists in early recognition and treatment of HI with the ultimate aim of reducing the prevalence of brain injury caused by hypoglycemia. A previous statement on diagnosis and management of HI in Japan was published in 2017. The current document provides an updated guideline for management of infants and children with HI and includes potential accommodations for less-developed regions of the world where resources may be limited.

Nutrigenomics of inward rectifier potassium channels

Inwardly rectifying potassium (Kir) channels play a key role in maintaining the resting membrane potential and supporting potassium homeostasis. There are many variants of Kir channels, which are usually tetramers in which the main subunit has two trans-membrane helices attached to two N- and C-terminal cytoplasmic tails with a pore-forming loop in between that contains the selectivity filter. These channels have domains that are strongly modulated by molecules present in nutrients found in different diets, such as phosphoinositols, polyamines and Mg²⁺. These molecules can impact these channels directly or indirectly, either allosterically by modulation of enzymes or via the regulation of channel expression. A particular type of these channels is coupled to cell metabolism and inhibited by ATP (KATP channels, essential for insulin release and for the pathogenesis of metabolic diseases like diabetes mellitus). Genomic changes in Kir channels have a significant impact on metabolism, such as conditioning the nutrients and electrolytes that an individual can take. Thus, the nutrigenomics of ion channels is an important emerging field in which we are attempting to understand how nutrients and diets can affect the activity and expression of ion channels and how genomic changes in such channels may be the basis for pathological conditions that limit nutrition and electrolyte intake. In this contribution we briefly review Kir channels, discuss their nutrigenomics, characterize how different components in the diet affect their function and expression, and suggest how their genomic changes lead to pathological phenotypes that affect diet and electrolyte intake.

Watchful waiting versus pharmacological management of small-for-gestational-age infants with hyperinsulinemic hypoglycemia

Introduction

Given that reports on severe diazoxide (DZX) toxicity are increasing, we aimed to understand if the short-term clinical outcomes of small-for-gestational-age (SGA) infants with hyperinsulinemic hypoglycemia (HH) managed primarily by supportive care, termed watchful waiting (WW), are different from those treated with DZX.

Method

A real-life observational cohort study was conducted from 1 September 2014 to 30 September 2020. The WW or DZX management decision was based on clinical and biochemical criteria. We compared central line duration (CLD), postnatal length of stay (LOS), and total intervention days (TIDs) among SGA-HH infants treated with DZX versus those on a WW approach. Fasting studies determined the resolution of HH.

Result

Among 71,836 live births, 11,493 were SGA, and 51 SGA infants had HH. There were 26 and 25 SGA-HH infants in the DZX and WW groups, respectively. Clinical and biochemical parameters were similar between groups. The median day of DZX initiation was day 10 of life (range 4-32), at a median dose of 4 mg/kg/day (range 3-10). All infants underwent fasting studies. Median CLD [DZX, 15 days (6-27) vs. WW, 14 days (5-31), P = 0.582] and postnatal LOS [DZX, 23 days (11-49) vs. WW, 22 days (8-61), P = 0.915] were comparable. Median TID was >3-fold longer in the DZX than the WW group [62.5 days (9-198) vs. 16 days (6-27), P < 0.001].

Conclusion

CLD and LOS are comparable between WW and DZX groups. Since fasting studies determine the resolution of HH, physicians should be aware that clinical intervention of DZX-treated SGA-HH patients extends beyond the initial LOS.

[Electroencephalogram features in children with congenital hyperinsulinism treated according to the international protocol in Russian Federation]

BACKGROUND

Congenital hyperinsulinism (CHI) is a rare life-threatening disease characterised by persistent hypoglycaemia as a result of inappropriate insulin secretion, which can lead to irreversible neurological defects in infants.

AIM

To evaluate neurophysiological characteristics of central nervous system in children with congenital hyperinsulinism treated according to the international protocol in Russian Federation.

MATERIALS AND METHODS

Our retrospective, prospective cohort study included 73 patients who received treatment for CHI according to the current international protocol at different departments of the Almazov National Medical Research Centre from 2017 to 2022. All patients underwent a comprehensive examination, including electroencephalography (EEG).

RESULTS

Among 73 patients with CHI, 35% (23) had focal form of the disease, 65% had non-focal form (49% (39) - diffuse form, 16% (11) - atypical form). All patients with focal form of CHI had a recovery as an outcome.Analysing the EEG data we found that paroxysmal activity was recorded in 23 patients (32%), 50 patients did not have paroxysmal activity (68%). Diffuse changes were observed in 47 patients (64%), whereas 26 patients (36%) were absent of it. By constructing Kaplan-Meier curves we found that the alpha rhythm is formed significantly (p=0.026) earlier in patients with a focal form of CHI.

CONCLUSION

CHI patients treated according to the international guidelines in Russian Federation show rather positive neurological outcome. We established that alpha rhythm earliest formation is associated with focal form of CHI.

Clinical and laboratory evaluation of children with congenital hyperinsulinism: a single center experience

OBJECTIVES

To evaluate and present the data regarding clinical, laboratory, radiological and the results of molecular genetic analysis of patients with hyperinsulinemic hypoglycemia in our clinics.

METHODS

A total of 9 patients with CHI followed at Istanbul Medipol University. Data related to gender, age at presentation, birth weight, gestational age, consanguinity, glucose and insulin levels at diagnosis, treatment modalities, response to treatment, the results of genetic analysis and radiological evaluation were gathered from the files.

RESULTS

The oldest age at presentation was 6 months. K_ATP channel mutation was detected in 55% (n: 5). Diazoxide unresponsiveness was seen in 55% (n: 5). Octreotide was effective in 3 of them. ¹⁸F-DOPA PET performed in 4 diazoxide unresponsive patients revealed focal lesion in 3 of them. Spontaneous remission rate was 66% (n:6). All the patients with normal genetic result achieved spontaneous remission. Spontaneous remission was even noted in diazoxide unresponsive patients and in patients with focal lesion on ¹⁸F-DOPA PET.

CONCLUSIONS

Clinical presentation of patients with congenital hypereinsulinism is heterogeneous. Spontaneous remission rate is quite high even in patients with severe clinical presentation. It is important to develop methods that can predict which patients will have spontaneous remission. Reporting the clinical and laboratory data of each patient is important and will help to guide the management of patients with hyperinsulinemic hypoglycemia.

Safety and efficacy of low-dose diazoxide in small-for-gestational-age infants with hyperinsulinaemic hypoglycaemia

OBJECTIVES

Diazoxide (DZX) is the drug of choice for treating hyperinsulinaemic hypoglycaemia (HH), and it has potentially serious adverse effects. We studied the safety and efficacy of low-dose DZX in small-for-gestational-age (SGA) infants with HH.

DESIGN

An observational cohort study from 1 September 2014 to 31 September 2020.

SETTING

A tertiary Women's and Children's Hospital in Singapore.

PATIENTS

All SGA infants with HH.

INTERVENTION

Diazoxide, at 3-5 mg/kg/day.

MAIN OUTCOME MEASURES

Short-term outcomes; adverse drug events and fasting studies to determine 'safe to go home' and 'resolution' of HH.

RESULTS

Among 71 836 live births, 11 493 (16%) were SGA. Fifty-six (0.5%) SGA infants with HH were identified, of which 27 (47%) with a mean gestational age of 36.4±2 weeks and birth weight of 1942±356 g required DZX treatment. Diazoxide was initiated at 3 mg/kg/day at a median age of 10 days. The mean effective dose was 4.6±2.2 mg/kg/day, with 24/27 (89%) receiving 3-5 mg/kg/day. Generalised hypertrichosis occurred in 2 (7.4%) and fluid retention in 1 (3.7%) infant. A fasting study was performed before home while on DZX in 26/27 (96%) cases. Diazoxide was discontinued at a median age of 63 days (9-198 days), and resolution of HH was confirmed in 26/27 (96%) infants on passing a fasting study.

CONCLUSION

Our study demonstrates that low-dose DZX effectively treats SGA infants with HH as measured by fasting studies. Although the safety profile was excellent, minimal adverse events were still observed with DZX, even at low doses.

A case of severe neonatal transient hyperinsulinemic hypoglycaemia without identifiable risk factors: a case report

Background

Neonatal hypoglycaemia is one of the major metabolic disorders that causes irreversible brain injury. Assessing for maternal glucose metabolism disorders can predict and avoid this perinatal complication. Accordingly, diagnosing maternal gestational diabetes mellitus (GDM) is important in protecting neonatal neurological prognosis. However, there are various methods of screening for maternal GDM. The intervention for neonatal hypoglycaemia also varies within each guideline.

Case presentation

A female infant was born at 37 weeks of gestation by vaginal delivery with no asphyxia. Her mother had no abnormal findings, including glucose metabolism disorders, upon periodic prenatal visits. Upon routine examination at the first hour of life, the baby was lethargic, pale, hypotonic, and rarely cried. An emergent systemic evaluation was performed, and she was diagnosed with severe hyperinsulinemic hypoglycaemia with blood glucose of 11 mg/dL and insulin of 2.7 µU/mL. She was soon fed with milk and her symptoms of hypoglycaemia was resolved before receiving intravenous glucose infusion. Her blood glucose level reached 78 mg/dL 3 h after delivery. She was discharged home with her mother on day 6 of age without relapse of hypoglycaemia. Upon review, we determined that the mother was diagnosed with GDM during her previous pregnancy but not during this current pregnancy. The infant had no developmental delay upon check-up at 6 months.

Conclusions

The infant of this case was not a candidate for neonatal hypoglycaemia screening since her mother had no identifiable risk factors. This case suggests that previous maternal history of GDM might be the cause of neonatal hyperinsulinemic hypoglycaemia. Clinicians need to be aware of the possibility of hypoglycaemia among newborns with a maternal previous history of GDM, regardless of the mother’s current diagnosis. Immediate oral feeding can be one of the treatments, even for symptomatic neonatal severe hypoglycaemia, when rapid intravenous access is difficult. The present case also suggests the necessity of considering neonatal outcomes as well as maternal ones when screening for maternal disorders of glucose metabolism.

A double-blind, placebo-controlled, single-ascending dose study to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of HM15136, a novel long-acting glucagon analogue, in healthy subjects

AIM

To evaluate the safety and tolerability, pharmacokinetics, and pharmacodynamics of HM15136, a novel long-acting glucagon analogue under development, in healthy males and females presenting with no childbearing potential.

MATERIALS AND METHODS

A randomized, double-blind, placebo-controlled, single-ascending dose study was conducted in 56 subjects who randomly received a single subcutaneous dose of HM15136 or its matching placebo at a ratio of 6:2 at 10, 20, 30, 50, 80, 100, and 120 μg/kg.

RESULTS

All adverse events were mild and transient. Neither serious adverse events nor discontinuation as a result of adverse events occurred. The most frequent adverse drug reaction was nausea (5.3%, only in the 100- and 120-μg/kg groups). HM15136, particularly at doses of 50 μg/kg or higher, increased fasting blood glucose, with a maximum increase and area under the curve of 1.5 mmol/L at day 10 (P = .006) and 166.3 day·mmol/L (P = .022) at the dose of 80 μg/kg, while suppressing the secretion of endogenous glucagon, which continued until day 17. HM15136 also significantly reduced gluconeogenic and ketogenic amino acids. Compensatory changes in endogenous insulin and incretin hormones by HM15136 were not apparent. HM15136 was slowly but steadily absorbed and reached a peak concentration at 46-68 hours after a single subcutaneous injection. HM15136 was eliminated with a terminal phase half-life of 77.1-101.1 hours.

CONCLUSIONS

A single subcutaneous dose of HM15136 at 10-120 μg/kg was safe and well tolerated. The long half-life of HM15136, coupled with an increase in blood glucose for ~2 weeks, may warrant a weekly dosing regimen.

Whole-exome sequencing analysis of a Japanese patient with hyperinsulinemia and liver dysfunction

Hyperinsulinemia is often observed in obese subjects because of insulin resistance, but it may occur in nonobese subjects with unknown etiology. A 72-year-old man was admitted to our hospital for the examination of hyperinsulinemia, reactive hypoglycemia, and liver dysfunction. The patient’s body mass index was 23.7 kg/m², but he had an elevated visceral fat area (125 cm²). His laboratory data showed mildly elevated liver enzymes, whereas plasma fasting glucose and serum insulin levels were 91 mg/dL and 52.3 μU/mL, respectively. In a 75-g oral glucose tolerance test, the serum insulin level reached the highest value of 1124 μU/mL at 180 minutes. There was no obvious etiology except for mild liver steatosis shown by liver biopsy. We suspected genetic abnormalities related to hyperinsulinemia. We performed whole-exome sequencing (WES) analyses and identified a heterozygous nonsense variant p.R924X in the insulin receptor (INSR) gene, a novel heterozygous missense variant p.V416M in the AKT1 gene, and a novel hemizygous missense variant p.R310Q in the PHKA2 gene, which is the causative gene of hepatic injury as glycogen storage disease type IX. It was speculated that the INSR gene variant, in addition to visceral fat accumulation, was the main cause of hyperinsulinemia and reactive hypoglycemia, and the remaining 2 variants were also partly responsible for hyperinsulinemia. WES analysis revealed candidate gene variants of hyperinsulinemia and hepatic-type glycogenosis. Thus, WES analysis may be a useful tool for clarifying the etiology when unexplained genetic pathophysiological conditions are suspected.

Case report: Congenital hyperinsulinemia with ABCC8 gene mutations

BACKGROUND

Congenital hyperinsulinemia (CHI) is an inherited disease of abnormal insulin secretion and is the main cause of persistent and intractable hypoglycemia in infants. The aim of this case report was to investigate the genetic mechanisms and treatment of CHI in an affected patient.

CASE SUMMARY

We collected clinical data from, and performed gene capture, high-throughput gene sequencing analysis, and Sanger sequencing validation, in a child with CHI and his family to identify the causative gene mutations. Two heterozygous pathogenic mutations in the ATP-binding cassette subfamily C member 8 (ABCC8) gene were detected in the child: c.863G>A (p.Trp288Ter) in exon 6 and c.2506C>T (p.Arg836Ter) in exon 21. Sanger sequencing showed that c.863G>A was inherited from heterozygous mutations in the paternal line and c.2506C>T from heterozygous mutations in the maternal line.

CONCLUSION

The child was a CHI with a biallelic recessive heterozygous mutations in ABCC8 resulting in impairment of its encoded ATP-sensitive potassium (KATP) channel, poor response to diazoxide treatment, and developed diabetes after subtotal pancreatectomy.

Genetic pathogenesis, diagnosis, and treatment of short-chain 3-hydroxyacyl-coenzyme A dehydrogenase hyperinsulinism

Congenital hyperinsulinism (CHI), a major cause of persistent and recurrent hypoglycemia in infancy and childhood. Numerous pathogenic genes have been associated with 14 known genetic subtypes of CHI. Adenosine triphosphate-sensitive potassium channel hyperinsulinism (KATP-HI) is the most common and most severe subtype, accounting for 40–50% of CHI cases. Short-chain 3-hydroxyacyl-coenzyme A dehydrogenase hyperinsulinism (SCHAD-HI) is a rare subtype that accounts for less than 1% of all CHI cases that are caused by homozygous mutations in the hydroxyacyl-coenzyme A dehydrogenase (HADH) gene. This review provided a systematic description of the genetic pathogenesis and current progress in the diagnosis and treatment of SCHAD-HI to improve our understanding of this disease.

Clinical and genetic characteristics of patients with congenital hyperinsulinism in 21 non-consanguineous families from Serbia

Persistent hypoglycaemia in newborns and infants is most commonly caused by congenital hyperinsulinism (CHI). Most CHI studies report outcomes in children from both consanguineous and non-consanguineous families which can affect the phenotype-genotype analysis. The aim of this study was to analyze characteristics of patients with CHI in 21 non-consanguineous families from Serbia. This retrospective cohort study included a total of 21 patients with CHI treated in the Mother and Child Healthcare Institute of Serbia during the past 20 years. The prevalence of macrosomia at birth was very low in our cohort (4.8%). Median age at presentation was 6 days, with seizures as the presenting symptom in 76% of patients. Only four patients (19%) were diazoxide unresponsive, and eventually underwent pancreatectomy. Genetic testing was performed in 15 patients and genetic diagnosis was confirmed in 60%, with all patients being heterozygous for detected mutations. The ABCC8 gene mutations were detected in 55.6%, GLUD1 in three patients (33.3%) with HIHA syndrome and one patient had HNF4A gene mutation and unusual prolonged hyperglycaemia lasting 6 days after diazoxide cessation. Neurodevelopmental deficits persisted in 33% of patients.Conclusion: This is the first study regarding CHI patients in Serbia. It suggests that in countries with low consanguinity rate, majority of CHI patients are diazoxide responsive. The most common mutations were heterozygous ABCC8, followed by GLUD1 and HNF4A mutations, suggesting the potential benefit of population-tailored genetic analysis approach, targeting the mutations causing CHI via dominant inheritance model in regions with low consanguinity rates. What is Known: • Persistent hypoglycaemia during infancy and early childhood is most commonly caused by congenital hyperinsulinism (CHI). • Consanguinity is a very important factor regarding the genetics and phenotype of CHI, increasing the risk of autosomal recessive genetic disorders, including the severe, diazoxide-unresponsive forms caused by recessive inactivating mutations in ABCC8 and KCNJ11. What is New: • Results of the present study which included CHI patients from 21 non-consanguineous families suggest that in countries with low consanguinity rates, majority of CHI patients can be diazoxide responsive, with most common mutations being heterozygous ABCC8, followed by GLUD1 and HNF4A mutations. • Unusually prolonged hyperglycaemic reaction to diazoxide treatment in a patient with HNF4A mutation was also described in the present study.

Glutamate Dehydrogenase as a Promising Target for Hyperinsulinism Hyperammonemia Syndrome Therapy

Hyperinsulinism-hyperammonemia syndrome (HHS) is a rare disease characterized by recurrent hypoglycemia and persistent elevation of plasma ammonia, and it can lead to severe epilepsy and permanent brain damage. It has been demonstrated that functional mutations of glutamate dehydrogenase (GDH), an enzyme in the mitochondrial matrix, are responsible for the HHS. Thus, GDH has become a promising target for the small molecule therapeutic intervention of HHS. Several medicinal chemistry studies are currently aimed at GDH, however, to date, none of the compounds reported has been entered clinical trials. This perspective summarizes the progress in the discovery and development of GDH inhibitors, including the pathogenesis of HHS, potential binding sites, screening methods, and research models. Future therapeutic perspectives are offered to provide a reference for discovering potent GDH modulators and encourage additional research that will provide more comprehensive guidance for drug development.

20p11.23-p11.21 deletion in a child with hyperinsulinemic hypoglycemia and GH deficiency: A case report

Some neonatal hypoglycemias have genetic origins. For instance, mutation in forkhead box protein A2 (FOXA2), located on chromosome 20p11.21, has recently been reported to cause hyperinsulinemic hypoglycemia and hypopituitarism. Here, we report a case of hyperinsulinemic hypoglycemia and GH deficiency (GHD) with 20p11.23-p11.21 deletion, which included FOXA2. The boy was diagnosed with hyperinsulinemic hypoglycemia during the neonatal period and subsequently administered diazoxide for treatment. His blood glucose levels gradually stabilized, and the diazoxide dosage was slowly reduced and ultimately fully weaned. The patient was discharged at the age of 29 d. Unfortunately, the patient experienced recurrent hypoglycemia at 3 mo, and diazoxide administration was re-initiated. Further examination, including chromosomal microarray analysis, revealed a 2.48-Mb 20p11.23-p11.21 deletion that encompassed FOXA2. In addition, severe GHD was detected, and magnetic resonance imaging of the brain revealed pituitary stalk interruption. Accordingly, GH replacement therapy was started at 0.175 mg/kg/wk, and blood glucose levels were stabilized. Our report suggests that there are pathological conditions that can cause both hyperinsulinemic hypoglycemia and hypopituitarism and reaffirms the importance of evaluating not only insulin and congenital metabolic disorders but also pituitary function in patients with hypoglycemia.

Hyperosmolar hyperglycemic syndrome induced by diazoxide and furosemide in a 5-year-old girl

Hyperglycemia and hyperosmolar hyperglycemic syndrome (HHS) are the rare adverse effects of diazoxide. Furosemide has been reported to worsen glucose tolerance and cause HHS. A 5-yr-old girl presented to the emergency department with complaints of tachycardia, polyuria, and lethargy for 1 wk prior to hospitalization. She was treated with two diuretics for aortic valve reflux disease and diazoxide for congenital hyperinsulinemia. She was diagnosed with HHS based on her serum glucose level of 529 mg/dL and serum osmotic pressure of 357 mOsm/kg. There were no findings suggestive of new-onset diabetes mellitus. She had fever on admission and, was diagnosed with a urinary tract infection. The blood diazoxide level at the time of hospitalization was 25 µg/dL. Diazoxide use, even in patients with low diazoxide levels, may cause hyperglycemia. Patients on diuretics and diazoxide must be carefully monitored, considering the risk of developing HHS.

Congenital hyperinsulinism in Gran Canaria, Canary Isles

INTRODUCTION

Congenital hyperinsulinism (CH) is a severe disorder characterised by the appearance of severe hypoglycaemia. Pathogenic mutations in the ABCC8 and KCNJ11 genes are the most frequent cause, although its appearance also been associated to mutations in other genes (GCK, GLUD1, HADH, HNF1A, HNF4A, SLC16A1, UCP2, HK1), and with different syndromes.

MATERIALS AND METHODS

Retrospective review of patients diagnosed with CH in this unit during the last 18 years (2001-2018). Genetic analysis included screening for 11 genes in genomic DNA from peripheral blood (ABCC8, GCK, GLUD1, HADH, HNF1A, HNF4A, INSR, KCNJ11, SLC16A1, UCP2, and SLC25A15).

OBJECTIVE

To carry out a clinical and genetic characterisation of the diagnosed cases of CH in Gran Canaria.

RESULTS

There have been 10 cases of persistent HC since 2001. Seven of them had mutations in the ABCC8 gene, one in the HNF4α gene, and in two patients, no pathogenic mutations were found in the analysed genes. Four patients presented with previously undescribed mutations. Pancreatectomy was performed in two of the cases. The minimum insulin value detected in hypoglycaemia was 6.81 µIU/mL. The incidence of persistent CH for Gran Canaria and Lanzarote is 1/15,614.

CONCLUSIONS

Four patients had previously undescribed mutations. The most frequently affected gene was ABCC8. Pancreatectomy was required in 20% of the patients. An insulin value of ≥6.81 µIU/mL was observed in all patients at the time of diagnosis. The incidence of CH in Gran Canaria is high.

18F-FDOPA and 68Ga-dotatate PET imaging in congenital hyperinsulinism

Congenital hyperinsulinism (CHI) occurs most commonly in infants but may also be discovered in older children. It presents with recurrent episodes of hypoglycemia due to high endogenous insulin levels. There is a focal and diffuse form of the disease depending on the extent of pancreatic involvement. Hyperplasia of the islet cells results in hyperfunctioning pancreatic β cells and the ensuing clinical disease. Medical treatment fails in several patients and surgery has been shown to be very effective in improving prognosis and even resolution of disease in the focal form. Several genetic mutations have been uncovered and these may also be predictive of prognosis. Anatomical imaging alone including ultrasound, CT and MRI are rarely able to detect any abnormality in the pancreas. PET plays a major role in the distinction between the focal and diffuse forms of the disease. It also guides surgical intervention by providing information on the location of the focal hyperfunctioning islet cells. Imaging children and infants in this disease is quite challenging. We propose to show the benefit of using two PET tracers in this disease. ¹⁸F-FDOPA has been used quite successfully in the evaluation of CHI. ⁶⁸Ga-DOTATATE has also been described to be helpful although inferior to ¹⁸F-FDOPA. We illustrate imaging of CHI patients in 3 different scans and briefly review the literature. ¹⁸F-FDOPA as described in the literature is superior but when unavailable ⁶⁸Ga-DOTATATE may be a reasonable alternative.

Marked clinical heterogeneity in congenital hyperinsulinism due to a novel homozygous ABCC8 mutation

BACKGROUND

The most severe forms of congenital hyperinsulinism (CHI) are caused by inactivating mutations of two KATP channel genes, KCNJ11 and ABCC8. Unresponsiveness to diazoxide and need for subtotal pancreatectomy can usually be predicted by genetic form, particularly biallelic mutations in KATP channel genes. A few reports indicated marked clinical heterogeneity in siblings with identical biallelic mutations in ABCC8. The clinical heterogeneity in biallelic KATP CHI was speculated to be caused by epigenetic and environmental factors or related to differences in splicing factor machinery.

OBJECTIVE

To elucidate the clinical pathophysiology, especially heterogeneity, among three cases with CHI caused by a homogenous novel mutation.

PATIENTS AND METHODS

We report a case series that includes two siblings and one unrelated individual with CHI caused by a homogenous 1-bp deletion around the splice acceptor site at the exon 35 mutation of ABCC8, which exhibited markedly distinct phenotypes. To assess the effect of the mutation on splicing, we performed digital droplet polymerase chain reaction (ddPCR) on normal pancreas tissue and a patient's lymphocytes.

RESULTS

ddPCR of ABCC8 cDNA revealed that expression of exon 35 and its upstream and downstream regions did not differ. These data suggested that clinical heterogeneity may not be caused by differences in splicing factor machinery.

CONCLUSION

The phenotypic variation in homozygotes could not be explained by splicing abnormalities. Though early genetic diagnosis of KATP CHI could contribute to selecting appropriate therapeutic options, more deliberate selection of therapeutic options in diffuse CHI due to biallelic ABCC8 mutations may be required.

Congenital Hyperinsulinism

Hyperinsulinemic hypoglycemia (HH) is fairly common in neonates, particularly those born to diabetic mothers and those who are either large or small for gestational age. Immediate management of the disease focuses on achieving normoglycemia through frequent high-calorie feedings and/or intravenous glucose administration. Glucagon may be used for unstable infants in whom intravenous access cannot be obtained and enteral feedings cannot be administered. HH that persists despite these interventions should raise concern for congenital hyperinsulinism (CHI), prompting clinicians to perform a thorough evaluation. CHI consists of a group of genetic disorders in which inappropriate insulin secretion results in persistent hypoglycemia. Defects can occur in the various genes that regulate the pathway for insulin secretion in the pancreatic β-cells. Pharmacologic therapies are used for long-term management of the disease coupled with either curative or therapeutic surgical intervention. Because of the developing brain's high demand for glucose, these infants are at increased risk for hypoglycemic brain injury. This review will describe the pathogenesis of CHI, outlining the more common genetic mutations and associated syndromes. We will also discuss the clinical presentation, diagnosis, and management of CHI while providing insight into the overall prognosis.

Successful treatment of adult-onset nesidioblastosis by continuous subcutaneous octreotide infusion in a patient on hemodialysis

Octreotide may be useful in noninsulinoma pancreatogenous hypoglycemia syndrome with nesidioblastosis patients who was on hemodialysis. Continuous octreotide subcutaneous infusion can reduce side-effects and stabilize plasma glucose levels.

Case Report: A Difficult-to-Diagnose Case of Hyperinsulinemic Hypoglycemia Surgically Treated After Developing Acute Pancreatitis

The patient is a 28-year-old Japanese man diagnosed with severe congenital hyperinsulinemic-hypoglycemia six months after birth. Clinical records revealed no imaging evidence of pancreatic tumor at the time of diagnosis. Subsequently, he had developmental disorders and epilepsy caused by recurrent hypoglycemic attacks. The patient's hypoglycemia improved with oral diazoxide. However, he developed necrotizing acute pancreatitis at 28 years of age, thought to be due to diazoxide. Discontinuation of diazoxide caused persistent hypoglycemia, requiring continuous glucose supplementation by tube feeding and total parenteral nutrition. A selective arterial secretagogue injection test revealed diffuse pancreatic hypersecretion of insulin. He underwent subtotal distal (72%) pancreatectomy and splenectomy. There was no intraoperative visible pancreatic tumor. His hypoglycemia improved after the surgical procedure. The histopathological study revealed a high density of islets of Langerhans in the pancreatic body and tail. There were large islets of Langerhans and multiple neuroendocrine cell nests in the whole pancreas. Nests of neuroendocrine cells were also detected in lymph nodes. The pathological diagnosis was grade 1 neuroendocrine tumor (microinsulinomas) with lymph node metastases. This patient is a difficult-to-diagnose case of hyperinsulinemic hypoglycemia surgically treated after developing acute pancreatitis. We believe this is a unique case of microinsulinomas with lymph metastases diagnosed and treated as congenital hyperinsulinemic hypoglycemia for almost 28 years.

Hyperinsulinemic hypoglycemia in children and adolescents: Recent advances in understanding of pathophysiology and management

Hyperinsulinemic hypoglycemia (HH) is characterized by unregulated insulin release, leading to persistently low blood glucose concentrations with lack of alternative fuels, which increases the risk of neurological damage in these patients. It is the most common cause of persistent and recurrent hypoglycemia in the neonatal period. HH may be primary, Congenital HH (CHH), when it is associated with variants in a number of genes implicated in pancreatic development and function. Alterations in fifteen genes have been recognized to date, being some of the most recently identified mutations in genes HK1, PGM1, PMM2, CACNA1D, FOXA2 and EIF2S3. Alternatively, HH can be secondary when associated with syndromes, intra-uterine growth restriction, maternal diabetes, birth asphyxia, following gastrointestinal surgery, amongst other causes. CHH can be histologically characterized into three groups: diffuse, focal or atypical. Diffuse and focal forms can be determined by scanning using fluorine-18 dihydroxyphenylalanine-positron emission tomography. Newer and improved isotopes are currently in development to provide increased diagnostic accuracy in identifying lesions and performing successful surgical resection with the ultimate aim of curing the condition. Rapid diagnostics and innovative methods of management, including a wider range of treatment options, have resulted in a reduction in co-morbidities associated with HH with improved quality of life and long-term outcomes. Potential future developments in the management of this condition as well as pathways to transition of the care of these highly vulnerable children into adulthood will also be discussed.

Intraoperative ultrasound imaging in the surgical treatment of congenital hyperinsulinism: prospective, blinded study

Background

In congenital hyperinsulinism (CHI), preoperative prediction of the histological subtype (focal, diffuse, or atypical) relies on genetics and 6-[¹⁸F]fluoro-l-3,4-dihydroxyphenylalanine (¹⁸F-DOPA) PET–CT. The scan also guides the localization of a potential focal lesion along with perioperative frozen sections. Intraoperative decision-making is still challenging. This study aimed to describe the characteristics and potential clinical impact of intraoperative ultrasound imaging (IOUS) during CHI surgery.

Methods

This was a prospective, observational study undertaken at an expert centre over a 2-year interval. IOUS was performed blinded to preoperative diagnostic test results (genetics and ¹⁸F-DOPA PET–CT), followed by unblinding and continued IOUS during pancreatic resection. Characteristics and clinical impact were assessed using predefined criteria.

Results

Eighteen consecutive, surgically treated patients with CHI, with a median age of 5.5 months, were included (focal 12, diffuse 3, atypical 3). Focal lesions presented as predominantly hypoechoic, oval lesions with demarcated or blurred margins. Patients with diffuse and atypical disease had varying echogenicity featuring stranding and non-shadowing hyperechoic foci in three of six, whereas these characteristics were absent from those with focal lesions. The blinded IOUS-based subclassification was correct in 17 of 18 patients; one diffuse lesion was misclassified as focal. IOUS had an impact on the surgical approach in most patients with focal lesions (9 of 12), and in those with diffuse (2 of 3) and atypical (2 of 3) disease when the resection site was close to the bile or pancreatic duct.

Conclusion

Uniform IOUS characteristics made all focal lesions identifiable. IOUS had a clinical impact in 13 of 18 patients by being a useful real-time supplementary modality in terms of localizing focal lesions, reducing the need for frozen sections, and preserving healthy tissue and delicate structures.

Consensus guideline for the diagnosis and management of mannose phosphate isomerase-congenital disorder of glycosylation

Mannose phosphate isomerase-congenital disorder of glycosylation (MPI-CDG) deficiency is a rare subtype of congenital disorders of protein N-glycosylation. It is characterised by deficiency of MPI caused by pathogenic variants in MPI gene. The manifestation of MPI-CDG is different from other CDGs as the patients suffer dominantly from gastrointestinal and hepatic involvement whereas they usually do not present intellectual disability or neurological impairment. It is also one of the few treatable subtypes of CDGs with proven effect of oral mannose. This article covers a complex review of the literature and recommendations for the management of MPI-CDG with an emphasis on the clinical aspect of the disease. A team of international experts elaborated summaries and recommendations for diagnostics, differential diagnosis, management, and treatment of each system/organ involvement based on evidence-based data and experts' opinions. Those guidelines also reveal more questions about MPI-CDG which need to be further studied.

Nationwide survey of endogenous hyperinsulinemic hypoglycemia in Japan (2017-2018): Congenital hyperinsulinism, insulinoma, non-insulinoma pancreatogenous hypoglycemia syndrome and insulin autoimmune syndrome (Hirata's disease)

AIMS/INTRODUCTION

We aimed to investigate the nationwide incidence, treatment details and outcomes of patients with endogenous hyperinsulinemic hypoglycemia (EHH), including those with transient/persistent congenital hyperinsulinism (CHI), insulinoma, non-insulinoma pancreatogenous hypoglycemia syndrome and insulin autoimmune syndrome (Hirata's disease) in Japan.

MATERIALS AND METHODS

A nationwide, questionnaire-based survey was carried out to determine the number of patients with EHH who were treated for hypoglycemia or hypoglycemia-related complications in 2017-2018. The questionnaires were sent to all hospitals in Japan with >300 beds, and with pediatric and/or adult clinics likely managing EHH patients. The secondary questionnaires were sent to obtain the patients' date of birth, sex, age at onset, treatment details and post-treatment outcomes.

RESULTS

A total of 447 patients with CHI (197 transient CHI, 225 persistent CHI and 25, unknown histology), 205 with insulinoma (118 benign, 18 malignant and 69 unknown subtype), 111 with non-insulinoma pancreatogenous hypoglycemia syndrome (33 post-gastric surgery HH, 57 postprandial HH, 10 nesidioblastosis and 11 unknown subtype) and 22 with insulin autoimmune syndrome were identified. Novel findings included: (i) marked improvement in the prognosis of persistent CHI over the past 10 years; (ii) male dominance in the incidence of transient CHI; (iii) non-insulinoma pancreatogenous hypoglycemia syndrome emerging as the second most common form of EHH in adults; (iv) frequent association of diabetes mellitus with insulin autoimmune syndrome; and (v) frequent post-treatment residual hypoglycemia and impaired quality of life.

CONCLUSIONS

The first nationwide, all age group survey of EHH showed the current status of each type of EHH disorder and the unmet needs of the patients.

Higher C-peptide levels and glucose requirements may identify neonates with transient hyperinsulinism hypoglycemia who will benefit from diazoxide treatment

The aim of the study was to characterize factors that may serve as clinical tools to identify neonates with transient neonatal hyperinsulinism hypoglycemia (HH) who may benefit from diazoxide treatment. This retrospective study included 141 neonates with transient HH (93 males) of whom 34 (24%) were treated with diazoxide. Diazoxide treatment was started at median age of 13 days (range 5-35) and discontinued at median age of 42 days (range 14-224). The maximal dose was 7.1 ± 2.3 mg/kg/day. Diazoxide-treated neonates required a higher glucose infusion rate (GIR) compared with non-treated neonates (16.6 ± 3.4 vs. 10.4 ± 4.0 mg/kg/min, respectively, P < .01), had a longer duration of intravenous fluids (15.9 ± 9.3 vs. 7.8 ± 6.5 days, P < .01), a longer hospitalization (32.8 ± 22.7 vs. 20.4 ± 13.4 days, P < .01), a longer duration of carbohydrate supplementation (38.9 ± 40.4 vs. 17.8 ± 21.4 days, P < .01), and higher mean C-peptide levels on "critical sample" (1.4 ± 0.9 vs. 0.8 ± 0.5 ng/ml, P < .01). Their insulin levels also tended to be higher (3.5 ± 2.9 vs. 2.2 ± 3.8 μU/ml, P = .07). A stepwise logistic regression model revealed that significant predictors of prolonged HH were maximal GIRs (odds ratio (OR) 1.56, 95%; confidence interval (CI) 1.3-1.88, P < .001) and C-peptide levels (OR 3.57, 95%; CI 1.3-12.1, P = .005).Conclusion: Higher C-peptide levels and higher GIR requirements may serve as clinical tools to identify neonates with transient HH who may benefit from diazoxide treatment.What is Known:• Neonates with transient hyperinsulinism usually do not require treatment beyond glucose supplementation due to its self-limited clinical course, but some may benefit from diazoxide treatment.What is New:• Higher C-peptide levels and higher GIR requirements may serve as clinical tools to identify neonates with transient HH who may benefit from diazoxide treatment.• The incidence of prolonged neonatal HH is higher than the currently accepted figures.

Identification of a compound heterozygous inactivating ABCC8 gene mutation responsible for young-onset diabetes with exome sequencing

Activating mutations in the ABCC8 gene cause diabetes and inactivating mutations usually cause hyperinsulinemic hypoglycemia in infancy. Patients with hypoglycemia in infancy due to a heterozygous inactivating mutation have been reported to occasionally progress to diabetes later in life. We explored the gene responsible for diabetes in two brothers, who were suspected to have diabetes at 15 and 18 years-of-age, respectively, with whole exome sequencing, and identified a compound heterozygous ABCC8 gene mutation (p.Arg168Cys and p.Arg1421Cys). Although their father and mother were heterozygous carriers of the p.Arg168Cys and the p.Arg1421Cys mutation, respectively, neither parent had diabetes. These mutations have been reported to be responsible for hypoglycemia in infancy and function as an inactivating mutation. Our results suggest that the inactivating ABCC8 gene mutation is also important in the etiology of diabetes.

Clinical Efficacy Evaluation of Sirolimus in Congenital Hyperinsulinism

BACKGROUND

Congenital hyperinsulinism (CHI) is a rare and life-threatening genetic disorder. Sirolimus as a mammalian target of rapamycin inhibitor may be helpful in patients with CHI who do not respond well to other treatments including diazoxide and octreotide. However, the safety and efficacy of this therapy are still unclear. This study aimed to evaluate the potential therapeutic effects of sirolimus in CHI patients with mutations in the ABCC8 and KCNJ11 genes.

METHODS

During the period of this follow-up study, every child with a confirmed diagnosis of unresponsive CHI underwent genetic evaluation. Among those who had positive genetic testing, six families agreed to participate in this study. The participants were evaluated for ABCC8, KCNJ11, or HNF4α gene mutations by polymerase chain reaction (PCR) sequencing. The participants who were unresponsive to diazoxide and octreotide therapy received 0.5 mg/m²/d of sirolimus, and the dose was gradually increased until a serum concentration of 5-15 ng/ml was achieved. Then, the participants were followed up for any possible complications.

RESULTS

Among the study participants, only one neonate was completely free of hypoglycemia after one year of follow-up, whereas three others experienced a partial reduction in hypoglycemic episodes over six months. One neonate underwent pancreatectomy despite receiving sirolimus. The oldest participant with a mutation in the ABCC8 gene responded well to sirolimus therapy after surgery and remained asymptomatic for 18 months.

CONCLUSION

This study suggested that sirolimus therapy needs further evaluation to determine which patients will benefit the most. The genetic basis of CHI may have possible implications for determining the patient's response.

Stimulus-Secretion Coupling in Beta-Cells: From Basic to Bedside

Insulin secretion in humans is usually induced by mixed meals, which upon ingestion, increase the plasma concentration of glucose, fatty acids, amino acids, and incretins like glucagon-like peptide 1. Beta-cells can stay in the off-mode, ready-mode or on-mode; the mode-switching being determined by the open state probability of the ATP-sensitive potassium channels, and the activity of enzymes like glucokinase, and glutamate dehydrogenase. Mitochondrial metabolism is critical for insulin secretion. A sound understanding of the intermediary metabolism, electrophysiology, and cell signaling is essential for comprehension of the entire spectrum of the stimulus-secretion coupling. Depolarization brought about by inhibition of the ATP sensitive potassium channel, together with the inward depolarizing currents through the transient receptor potential (TRP) channels, leads to electrical activities, opening of the voltage-gated calcium channels, and exocytosis of insulin. Calcium- and cAMP-signaling elicited by depolarization, and activation of G-protein-coupled receptors, including the free fatty acid receptors, are intricately connected in the form of networks at different levels. Activation of the glucagon-like peptide 1 receptor augments insulin secretion by amplifying calcium signals by calcium induced calcium release (CICR). In the treatment of type 2 diabetes, use of the sulfonylureas that act on the ATP sensitive potassium channel, damages the beta cells, which eventually fail; these drugs do not improve the cardiovascular outcomes. In contrast, drugs acting through the glucagon-like peptide-1 receptor protect the beta-cells, and improve cardiovascular outcomes. The use of the glucagon-like peptide 1 receptor agonists is increasing and that of sulfonylurea is decreasing. A better understanding of the stimulus-secretion coupling may lead to the discovery of other molecular targets for development of drugs for the prevention and treatment of type 2 diabetes.

Altered Serum Amino Acid and Acylcarnitine Profiles in Hyperinsulinemic Hypoglycemia and Ketotic Hypoglycemia

BACKGROUND

In addition to inborn metabolic disorders, altered metabolic profiles were reported to be associated with the risk and prognosis of some non-metabolic diseases, while as a rare metabolic disease, the overall secondary metabolic spectrum in congenital hyperinsulinemic hypoglycemia (HH) is largely undetermined. Therefore, we investigated metabolic profiles in HH patients and used ketotic hypoglycemia (KH) patients as a control cohort to unveil their distinct metabolic features.

METHODS

A total of 97 hypoglycemia children, including 74 with hyperinsulinemic hypoglycemia and 23 with ketotic hypoglycemia, and 170 euglycemia control subjects were studied retrospectively. Clinical and biochemical data were collected. The normoglycemic spectra of amino acids and acylcarnitines were determined by liquid chromatography tandem mass spectrometry. The serum insulin and fatty acid concentrations during standardized fasting tests in hypoglycemia patients were also collected. Receiver operating characteristic curve analysis was performed to screen potential biomarkers.

RESULTS

Among the normoglycemic spectra of amino acids, blood valine (p < 0.001), arginine (p < 0.001), threonine (p = 0.001), glutamate (p = 0.002), methionine (p = 0.005), ornithine (p = 0.008), leucine (p = 0.014), alanine (p = 0.017), proline (p = 0.031), citrulline (p = 0.042), aspartate (p = 0.046), and glycine (p = 0.048) levels differed significantly among the three groups. Significantly decreased levels of long- (C14:1, p < 0.001; C18, p < 0.001), medium- (C8, p < 0.001; C10, p < 0.001; C10:1, p < 0.001), and short-chain (C4-OH, p < 0.001; C5OH, p < 0.001) acylcarnitines were found in the hyperinsulinemic hypoglycemia group. Hyperinsulinemic hypoglycemia children with focal lesions and diffuse lesions had similar amino acid and acylcarnitine spectra. C10:1 < 0.09 μmol/L, threonine > 35 μmol/L, and threonine/C10:1 > 440 showed sensitivities of 81.1, 66.2, and 81.1% and specificities of 72.7, 78.3, and 81.8%, respectively, in distinguishing HH from KH.

CONCLUSIONS

We found significantly different altered serum amino acid and acylcarnitine profiles at normoglycemia, especially decreased C10:1 and increased threonine levels, between HH and KH children, which may reflect the insulin ketogenesis inhibition effect in HH patients; however, the detailed mechanisms and physiological roles remain to be studied in the future.

Possible New Strategies for the Treatment of Congenital Hyperinsulinism

OBJECTIVE

Congenital hyperinsulinism (CHI) is a rare disease characterized by persistent hypoglycemia as a result of inappropriate insulin secretion, which can lead to irreversible neurological defects in infants. Poor efficacy and strong adverse effects of the current medications impede successful treatment. The aim of the study was to investigate new approaches to silence β-cells and thus attenuate insulin secretion.

RESEARCH DESIGN AND METHODS

In the scope of our research, we tested substances more selective and more potent than the gold standard diazoxide that also interact with neuroendocrine ATP-sensitive K⁺ (K_ATP) channels. Additionally, K_ATP channel-independent targets as Ca²⁺-activated K⁺ channels of intermediate conductance (K_Ca3.1) and L-type Ca²⁺ channels were investigated. Experiments were performed using human islet cell clusters isolated from tissue of CHI patients (histologically classified as pathological) and islet cell clusters obtained from C57BL/6N (WT) or SUR1 knockout (SUR1^-/-) mice. The cytosolic Ca²⁺ concentration ([Ca²⁺]_c) was used as a parameter for the pathway regulated by electrical activity and was determined by fura-2 fluorescence. The mitochondrial membrane potential (ΔΨ) was determined by rhodamine 123 fluorescence and single channel currents were measured by the patch-clamp technique.

RESULTS

The selective K_ATP channel opener NN414 (5 µM) diminished [Ca²⁺]_c in isolated human CHI islet cell clusters and WT mouse islet cell clusters stimulated with 10 mM glucose. In islet cell clusters lacking functional K_ATP channels (SUR1^-/-) the drug was without effect. VU0071063 (30 µM), another K_ATP channel opener considered to be selective, lowered [Ca²⁺]_c in human CHI islet cell clusters. The compound was also effective in islet cell clusters from SUR1^-/- mice, showing that [Ca²⁺]_c is influenced by additional effects besides K_ATP channels. Contrasting to NN414, the drug depolarized ΔΨ in murine islet cell clusters pointing to severe interference with mitochondrial metabolism. An opener of K_Ca3.1 channels, DCEBIO (100 µM), significantly decreased [Ca²⁺]_c in SUR1^-/- and human CHI islet cell clusters. To target L-type Ca²⁺ channels we tested two already approved drugs, dextromethorphan (DXM) and simvastatin. DXM (100 µM) efficiently diminished [Ca²⁺]_c in stimulated human CHI islet cell clusters as well as in stimulated SUR1^-/- islet cell clusters. Similar effects on [Ca²⁺]_c were observed in experiments with simvastatin (7.2 µM).

CONCLUSIONS

NN414 seems to provide a good alternative to the currently used K_ATP channel opener diazoxide. Targeting K_Ca3.1 channels by channel openers or L-type Ca²⁺ channels by DXM or simvastatin might be valuable approaches for treatment of CHI caused by mutations of K_ATP channels not sensitive to K_ATP channel openers.

Clinical Management and Gene Mutation Analysis of Children with Congenital Hyperinsulinism in South China

OBJECTIVE

To explore the clinical presentation and molecular genetic characteristics of a cohort of congenital hyperinsulinism (CHI) patients from southern China and also to explore the most appropriate therapeutic approaches.

METHODS

We retrospectively reviewed a cohort of 65 children with CHI. Mutational analysis was performed for KCNJ11 and ABCC8 genes. The GLUD1 gene was sequenced in patients with hyperammonaemia. GCK gene sequencing was performed in those patients with no mutation identified in the ABCC8, KCNJ11 or GLUD1 genes.

RESULTS

ABCC8 mutations were identified in 16 (25%) of the cohort, GLUD1 mutations were identified in five children, and no KCNJ11 or GCK mutations were identified. Moreover, some unique features of ABCC8 gene mutations in southern Chinese CHI patients were found in this study. The most common mutation was a deletion/insertion mutation p.Thr1042GlnfsX75 was found in five unrelated patients, which possibly represents a relatively common mutation in southern China. Five novel ABCC8 mutations were detected. The mutations were p.Phe5SerfsX72, p.Gln273ArgfsX85, p.Leu724del, p.Asp1447Gly and IVS 25-1G>T. Five compound heterozygous mutations of ABCC8 gene were identified in this study, and three of these patients were diazoxide-responsive. Forty patients were diazoxide-responsive, 13 patients were diazoxide-unresponsive and 12 patients received dietary treatment only. A pancreatectomy was performed in 10 patients who were unresponsive to medical treatment.

CONCLUSION

To the best of our knowledge, this is the first study of CHI in south China. Mutations in ABCC8 are the most common causes of CHI in this cohort. Diazoxide and dietary treatment were effective in most patients. Multicentre studies are necessary to obtain the long-term follow-up characteristics of such patients at a national level.

Current and Emerging Agents for the Treatment of Hypoglycemia in Patients with Congenital Hyperinsulinism

Congenital hyperinsulinism (CHI) is the most common cause of persistent hypoglycmia in neonatles and children. The inappropriate secretion of insulin by the pancreatic β-cells produces recurrent hypoglycemia, which can lead to severe and permanent brain damage. CHI results from mutations in different genes that play a role in the insulin secretion pathway, and each differs in their responsiveness to medical treatment. Currently, the only available approved treatment for hyperinsulinism is diazoxide. Patients unresponsive to diazoxide may benefit from specialized evaluation including genetic testing and 18F-DOPA PET to identify those with focal forms of CHI. The focal forms can be cured by selective pancreatectomy, but the management of diazoxide-unresponsive diffuse CHI is a real therapeutic challenge. Current off-label therapies include intravenous glucagon, octreotide and long-acting somatostatin analogs; however, they are often insufficient, and a 98% pancreatectomy or continuous feeds may be required. For the first time in over 40 years, new drugs are being developed, but none have made it to market yet. In this review, we will discuss current on-label and off-label drugs and review the currently available data on the novel drugs under development.

Prevalence of Adverse Events in Children With Congenital Hyperinsulinism Treated With Diazoxide

CONTEXT

Diazoxide, the only U.S. Food and Drug Administration-approved drug to treat hyperinsulinemic hypoglycemia, has been associated with several adverse events, which has raised concerns about the safety of this drug. Existing reports are limited to small studies and case reports.

OBJECTIVE

To determine prevalence of and clinical factors associated with adverse events in infants and children treated with diazoxide.

DESIGN

Retrospective cohort study of children with hyperinsulinism (HI) treated with diazoxide between 2003 and 2014.

SETTING

The Congenital Hyperinsulinism Center at the Children's Hospital of Philadelphia.

PATIENTS

Children and infants with laboratory-confirmed diagnosis of HI.

MAIN OUTCOME MEASURES

Prevalence of pulmonary hypertension (PH), edema, neutropenia, thrombocytopenia, and hyperuricemia was determined. Tests of association and logistic regression were used to identify potential risk factors.

RESULTS

A total of 295 patients (129 female) met inclusion criteria. The median age at diazoxide initiation was 29 days (interquartile range, 10 to 142 days; n = 226 available start dates); 2.4% of patients were diagnosed with PH after diazoxide initiation. Children with PH (P = 0.003) or edema (P = 0.002) were born at earlier gestational age and more frequently had potential PH risk factors, including respiratory failure and structural heart disease (P < 0.0001 and P = 0.005). Other adverse events included neutropenia (15.6%), thrombocytopenia (4.7%), and hyperuricemia (5.0%).

CONCLUSION

In this large cohort, PH occurred in infants with underlying risk factors, but no identifiable risk profile emerged for other adverse events. The relatively high prevalence of neutropenia, thrombocytopenia, and hyperuricemia suggests the value in proactively screening for these side effects in children treated with diazoxide.

Congenital hyperinsulinism treated by surgical resection of the hyperplastic lesion which had been preoperatively diagnosed by 18F-DOPA PET examination in Japan: a nationwide survey

PURPOSE

Congenital hyperinsulinism is a rare disease, and the newly developed 18 fluoro-_L-dihydroxyphenylalanine-positron emission tomography (18F-DOPA PET) examination can detect hyperplastic lesions. Our purpose was to report the results of a nationwide survey on surgical treatment of congenital hyperinsulinism in Japan.

METHODS

A questionnaire was sent to the 159 accredited and affiliated training institutes certified as pediatric surgical institutes by the Japanese Association of Pediatric Surgeons, asking if they had encountered patients who underwent surgical treatment for congenital hyperinsulinism after 18F-DOPA PET examination from 2000 to 2017. Six institutes answered that they had treated such cases, and the total number of cases was 14.

RESULTS

18F-DOPA PET examination detected the focal lesion in 12 of the 14 cases. 18F-DOPA PET examination could accurately determine the site of the hyperplastic lesion in the pancreas in 11 (91.7%) of the 12 cases. All cases underwent surgical resection of the hyperplastic lesion at under 2 years of age.

CONCLUSION

Surgical resection of a focal hyperplastic lesion in the pancreas was a safe and effective treatment if the hyperplastic lesion was a focal lesion. However, it is necessary to check the exact distribution of the lesion by intraoperative pathologic examination of frozen sections.

Clinical and Molecular Spectrum of Glutamate Dehydrogenase Gene Defects in 26 Chinese Congenital Hyperinsulinemia Patients

OBJECTIVE

To characterize the genotype and phenotype of Chinese patients with congenital hyperinsulinism (CHI) caused by activating mutations in GLUD1, the gene that encodes mitochondrial enzyme glutamate dehydrogenase (GDH).

METHODS

The clinical data of glutamate dehydrogenase hyperinsulinism (GDH-HI) patients were reviewed, and gene mutations were confirmed by whole exome sequencing (WES) and Sanger DNA sequencing.

RESULTS

Twenty-six patients with GDH-HI heterozygous missense mutations were identified from 240 patients diagnosed as congenital hyperinsulinism over past 15 years. The median age at onset was 8 months (range: 1 day of life to 3 years). Seizure disorder was common in our cohort of patients (23/26). Four patients had normal serum ammonia levels; the median serum concentration was 101 μmol/L (range: 37-190 μmol/L). Hypoglycemic symptoms could be triggered by fasting or protein meals in all patients while blood glucose could be well controlled in all patients with diazoxide. Dosage of diazoxide could be reduced by protein restriction. Attempts to lower ammonia levels failed with different therapies such as protein restriction, benzoate, or N-carbamoyl glutamate. In follow-up, 15 of 26 patients had normal intelligence. Eleven patients developed epilepsy at the age of 6 months to 11 years. De novo mutations in GLUD1 were found in 24 cases, and dominant inheritance was observed in the other two; all were heterozygous. A total of 35% (9/26) patients carried c.1493C>T (p.S445L) mutation.

CONCLUSIONS

Phenotypic heterogeneity of GDH-HI patients was observed within the Chinese cohort in the present study. The fact that most patients had a GLUD1 p. S445L mutation implies that this site could be a hotspot in Chinese patients. A high frequency of GDH-HI with normal ammonia has been reported in this study. Hence, GLUD1 mutational analysis may be an important method to differential diagnosis of GDH-HI from other diazoxide-responsive CHI in Chinese patients.

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.