Long-Term Outcome and Treatment in Persistent and Transient Congenital Hyperinsulinism: A Finnish Population-Based Study

The Rising Incidence of Hyperinsulinemic Hypoglycemia: Connection With Maternal Health

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

Congenital hyperinsulinism (CHI) is a condition characterised by severe and recurrent hypoglycaemia in infants and young children caused by inappropriate insulin over-secretion. CHI is of heterogeneous aetiology with a significant genetic component and is often unresponsive to standard medical therapy options. The treatment of CHI can be multifaceted and complex, requiring multidisciplinary input. It is important to manage hypoglycaemia in CHI promptly as the risk of long-term neurodisability arising from neuroglycopaenia is high. The UK CHI consensus on the practice and management of CHI was developed to optimise and harmonise clinical management of patients in centres specialising in CHI as well as in non-specialist centres engaged in collaborative, networked models of care. Using current best practice and a consensus approach, it provides guidance and practical advice in the domains of diagnosis, clinical assessment and treatment to mitigate hypoglycaemia risk and improve long term outcomes for health and well-being.

Genetics and Natural History of Non-pancreatectomized Patients With Congenital Hyperinsulinism Due to Variants in ABCC8

CONTEXT

Patients with congenital hyperinsulinism due to ABCC8 variants generally present severe hypoglycemia and those who do not respond to medical treatment typically undergo pancreatectomy. Few data exist on the natural history of non-pancreatectomized patients.

OBJECTIVE

This work aims to describe the genetic characteristics and natural history in a cohort of non-pancreatectomized patients with congenital hyperinsulinism due to variants in the ABCC8 gene.

METHODS

Ambispective study of patients with congenital hyperinsulinism with pathogenic or likely pathogenic variants in ABCC8 treated in the last 48 years and who were not pancreatectomized. Continuous glucose monitoring (CGM) has been periodically performed in all patients since 2003. An oral glucose tolerance test was performed if hyperglycemia was detected in the CGM.

RESULTS

Eighteen non-pancreatectomized patients with ABCC8 variants were included. Seven (38.9%) patients were heterozygous, 8 (44.4%) compound heterozygous, 2 (11.1%) homozygous, and 1 patient carried 2 variants with incomplete familial segregation studies. Seventeen patients were followed up and 12 (70.6%) of them evolved to spontaneous resolution (median age 6.0 ± 4 years; range, 1-14). Five of these 12 patients (41.7%) subsequently progressed to diabetes with insufficient insulin secretion. Evolution to diabetes was more frequent in patients with biallelic variants in the ABCC8 gene.

CONCLUSION

The high remission rate observed in our cohort makes conservative medical treatment a reliable strategy for the management of patients with congenital hyperinsulinism due to ABCC8 variants. In addition, a periodic follow-up of glucose metabolism after remission is recommended, as a significant proportion of patients evolved to impaired glucose tolerance or diabetes (biphasic phenotype).

International Guidelines for the Diagnosis and Management of Hyperinsulinism

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. 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. 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.

Hyperinsulinemic Hypoglycemia Diagnosed in Childhood Can Be Monogenic

CONTEXT

Congenital hyperinsulinism (HI) is characterized by inappropriate insulin secretion despite low blood glucose. Persistent HI is often monogenic, with the majority of cases diagnosed in infancy. Less is known about the contribution of monogenic forms of disease in those presenting in childhood.

OBJECTIVE

We investigated the likelihood of finding a genetic cause in childhood-onset HI and explored potential factors leading to later age at presentation of disease.

METHODS

We screened known disease-causing genes in 1848 individuals with HI, referred for genetic testing as part of routine clinical care. Individuals were classified as infancy-onset (diagnosed with HI < 12 months of age) or childhood-onset (diagnosed at age 1-16 years). We assessed clinical characteristics and the genotypes of individuals with monogenic HI diagnosed in childhood to gain insights into the later age at diagnosis of HI in these children.

RESULTS

We identified the monogenic cause in 24% (n = 42/173) of the childhood-onset HI cohort; this was significantly lower than the proportion of genetic diagnoses in infancy-onset cases (74.5% [n = 1248/1675], P < 0.00001). Most (75%) individuals with genetically confirmed childhood-onset HI were diagnosed before 2.7 years, suggesting these cases represent the tail end of the normal distribution in age at diagnosis. This is supported by the finding that 81% of the variants identified in the childhood-onset cohort were detected in those diagnosed in infancy.

CONCLUSION

We have shown that monogenic HI is an important cause of hyperinsulinism presenting outside of infancy. Genetic testing should be considered in children with persistent hyperinsulinism, regardless of age at diagnosis.

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

For the past 70 years, controversy about hypoglycemia in newborn infants has focused on a numerical "definition of neonatal hypoglycemia", without regard to its mechanism. This ignores the purpose of screening newborns for hypoglycemia, which is to identify those with pathological forms of hypoglycemia and to prevent hypoglycemic brain injury. Recent clinical and basic research indicates that the three major forms of neonatal hypoglycemia are caused by hyperinsulinism (recognizing also that other rare hormonal or metabolic conditions may also present during this time frame). These include transitional hypoglycemia, which affects all normal newborns in the first few days after birth; perinatal stress-induced hypoglycemia in high-risk newborns, which afflicts ∼1 in 1,200 newborns; and genetic forms of congenital hyperinsulinism which afflict ∼1 in 10,000-40,000 newborns. (1) Transitional hyperinsulinism in normal newborns reflects persistence of the low glucose threshold for insulin secretion during fetal life into the first few postnatal days. Recent data indicate that the underlying mechanism is decreased trafficking of ATP-sensitive potassium channels to the beta-cell plasma membrane, likely a result of the hypoxemic state of fetal life. (2) Perinatal stress-induced hyperinsulinism in high-risk infants appears to reflect an exaggeration of this normal low fetal glucose threshold for insulin release due to more severe and prolonged exposure to perinatal hypoxemia. (3) Genetic hyperinsulinism, in contrast, reflects permanent genetic defects in various steps controlling beta-cell insulin release, such as inactivating mutations of the K _ATP-channel genes. The purpose of this report is to review our current knowledge of these three major forms of neonatal hyperinsulinism as a foundation for the diagnosis and management of hypoglycemia in newborn infants. This includes selection of appropriate interventions based on underlying disease mechanism; combined monitoring of both plasma glucose and ketone levels to improve screening for infants with persistent forms of hypoglycemia; and ultimately to ensure that infants at risk of persistent hyperinsulinemic hypoglycemia are recognized prior to discharge from the nursery.

Syndromic forms of congenital hyperinsulinism

Congenital hyperinsulinism (CHI), also called hyperinsulinemic hypoglycemia (HH), is a very heterogeneous condition and represents the most common cause of severe and persistent hypoglycemia in infancy and childhood. The majority of cases in which a genetic cause can be identified have monogenic defects affecting pancreatic β-cells and their glucose-sensing system that regulates insulin secretion. However, CHI/HH has also been observed in a variety of syndromic disorders. The major categories of syndromes that have been found to be associated with CHI include overgrowth syndromes (e.g. Beckwith-Wiedemann and Sotos syndromes), chromosomal and monogenic developmental syndromes with postnatal growth failure (e.g. Turner, Kabuki, and Costello syndromes), congenital disorders of glycosylation, and syndromic channelopathies (e.g. Timothy syndrome). This article reviews syndromic conditions that have been asserted by the literature to be associated with CHI. We assess the evidence of the association, as well as the prevalence of CHI, its possible pathophysiology and its natural course in the respective conditions. In many of the CHI-associated syndromic conditions, the mechanism of dysregulation of glucose-sensing and insulin secretion is not completely understood and not directly related to known CHI genes. Moreover, in most of those syndromes the association seems to be inconsistent and the metabolic disturbance is transient. However, since neonatal hypoglycemia is an early sign of possible compromise in the newborn, which requires immediate diagnostic efforts and intervention, this symptom may be the first to bring a patient to medical attention. As a consequence, HH in a newborn or infant with associated congenital anomalies or additional medical issues remains a differential diagnostic challenge and may require a broad genetic workup.

Congenital Hyperinsulinaemic Hypoglycaemia-A Review and Case Presentation

Hyperinsulinaemic hypoglycaemia (HH) is the most common cause of persistent hypoglycaemia in infants and children with incidence estimated at 1 per 50,000 live births. Congenital hyperinsulinism (CHI) is symptomatic mostly in early infancy and the neonatal period. Symptoms range from ones that are unspecific, such as poor feeding, lethargy, irritability, apnoea and hypothermia, to more serious symptoms, such as seizures and coma. During clinical examination, newborns present cardiomyopathy and hepatomegaly. The diagnosis of CHI is based on plasma glucose levels <54 mg/dL with detectable serum insulin and C-peptide, accompanied by suppressed or low serum ketone bodies and free fatty acids. The gold standard in determining the form of HH is fluorine-18-dihydroxyphenyloalanine PET ((18)F-DOPA PET). The first-line treatment of CHI is diazoxide, although patients with homozygous or compound heterozygous recessive mutations responsible for diffuse forms of CHI remain resistant to this therapy. The second-line drug is the somatostatin analogue octreotide. Other therapeutic options include lanreotide, glucagon, acarbose, sirolimus and everolimus. Surgery is required in cases unresponsive to pharmacological treatment. Focal lesionectomy or near-total pancreatectomy is performed in focal and diffuse forms of CHI, respectively. To prove how difficult the diagnosis and management of CHI is, we present a case of a patient admitted to our hospital.

Increased referrals for congenital hyperinsulinism genetic testing in children with trisomy 21 reflects the high burden of non-genetic risk factors in this group

BACKGROUND

Hyperinsulinism results from inappropriate insulin secretion during hypoglycaemia. Down syndrome is causally linked to a number of endocrine disorders including Type 1 diabetes and neonatal diabetes. We noted a high number of individuals with Down syndrome referred for hyperinsulinism genetic testing, and therefore aimed to investigate whether the prevalence of Down syndrome was increased in our hyperinsulinism cohort compared to the population.

METHODS

We identified individuals with Down syndrome referred for hyperinsulinism genetic testing to the Exeter Genomics Laboratory between 2008 and 2020. We sequenced the known hyperinsulinism genes in all individuals and investigated their clinical features.

RESULTS

We identified 11 individuals with Down syndrome in a cohort of 2011 patients referred for genetic testing for hyperinsulinism. This represents an increased prevalence compared to the population (2.5/2011 expected vs. 11/2011 observed, p = 6.8 × 10^-5 ). A pathogenic ABCC8 mutation was identified in one of the 11 individuals. Of the remaining 10 individuals, five had non-genetic risk factors for hyperinsulinism resulting from the Down syndrome phenotype: intrauterine growth restriction, prematurity, gastric/oesophageal surgery, and asparaginase treatment for leukaemia. For five individuals no risk factors for hypoglycaemia were reported although two of these individuals had transient hyperinsulinism and one was lost to follow-up.

CONCLUSIONS

Down syndrome is more common in patients with hyperinsulinism than in the population. This is likely due to an increased burden of non-genetic risk factors resulting from the Down syndrome phenotype. Down syndrome should not preclude genetic testing as coincidental monogenic hyperinsulinism and Down syndrome is possible.

Congenital Hyperinsulinism: Current Laboratory-Based Approaches to the Genetic Diagnosis of a Heterogeneous Disease

Congenital hyperinsulinism is characterised by the inappropriate release of insulin during hypoglycaemia. This potentially life-threatening disorder can occur in isolation, or present as a feature of syndromic disease. Establishing the underlying aetiology of the hyperinsulinism is critical for guiding medical management of this condition especially in children with diazoxide-unresponsive hyperinsulinism where the underlying genetics determines whether focal or diffuse pancreatic disease is present. Disease-causing single nucleotide variants affecting over 30 genes are known to cause persistent hyperinsulinism with mutations in the KATP channel genes (ABCC8 and KCNJ11) most commonly identified in children with severe persistent disease. Defects in methylation, changes in chromosome number, and large deletions and duplications disrupting multiple genes are also well described in congenital hyperinsulinism, further highlighting the genetic heterogeneity of this condition. Next-generation sequencing has revolutionised the approach to genetic testing for congenital hyperinsulinism with targeted gene panels, exome, and genome sequencing being highly sensitive methods for the analysis of multiple disease genes in a single reaction. It should though be recognised that limitations remain with next-generation sequencing with no single application able to detect all reported forms of genetic variation. This is an important consideration for hyperinsulinism genetic testing as comprehensive screening may require multiple investigations.

Recent updates in the management of infants and children with hyperinsulinism

PURPOSE OF REVIEW

To highlight recent advances in early diagnosis and the changing treatment paradigm for hyperinsulinism (HI) which can result in shorter hospitalizations, higher rates of cure and improved neurological outcome.

RECENT FINDINGS

Recent literature has shown that following publication of the pediatric endocrinology society guidelines for diagnosing hypoglycemia there have been higher rates of diagnosis of acquired and genetic HI. Studies of neurological outcome have found that poor outcomes are associated with delay between initial hypoglycemia and instigation of treatment for HI, hypoglycemic seizures and frequency of glucose <20 mg/dL. Rapid genetic testing can decrease the time from the discovery of diazoxide unresponsiveness to referral to multidisciplinary centers with the availability of 18-F-L 3,4-Dihydroxyphenylalanine positron emission tomography (18F-DOPA PET). Proper selection of patients for 18F-DOPA PET and careful interpretation of the images can result in greater than 90% cure for patients with focal HI.

SUMMARY

Recent advances in the early diagnosis of HI and rapid turnaround genetic testing can lead to prompt transfer to centers with multidisciplinary care teams where proper selection of patients for 18F-DOPA PET scan gives the best opportunity for cure for patients with focal disease. Minimizing severe hypoglycemia maximizes the opportunity for improved neurological outcome.