Background and ObjectiveKabuki syndrome (KS), caused by pathogenic variants in KMT2D or KDM6A, is associated with hyperinsulinaemic hypoglycaemia (HH) in 0.3%‐4% of patients. We characterized the clinical, biochemical and molecular data of children with KS and HH compared to children with KS without HH in a multicentre meta‐analysis.MethodsData of seven new and 17 already published children with KS and HH were compared to 373 recently published KS patients without HH regarding molecular and clinical characteristics.ResultsSeven new patients were identified with seven different pathogenic variants in KDM6A (n = 4) or KMT2D (n = 3). All presented with HH on the first day of life and were responsive to diazoxide. KS was diagnosed between 9 months and 14 years of age. In the meta‐analysis, 24 KS patients with HH had a significantly higher frequency of variants in KDM6A compared to 373 KS patients without HH (50% vs 11.5%, P < .001), and KDM6A‐KS was more likely to be associated with HH than KMT2D‐KS (21.8% vs. 3.5%, P < .001). Sex distribution and other phenotypic features did not differ between KS with and without HH.ConclusionThe higher incidence of HH in KDM6A‐KS compared to KMT2D‐KS indicates that KDM6A loss of function variants predispose more specifically to beta cell dysfunction compared to KMT2D variants. As difficulties to assign syndromic characteristics to KS in early infancy often lead to delayed diagnosis, genetic testing for KS should be considered in children with HH, especially in the presence of other extrapancreatic/syndromic features.

ObjectiveAim was to identify hypotheses why adverse neurodevelopment still occurs in children with transient or persistent hyperinsulinism despite improvements in long-term treatment options during the last decades.Material and MethodsA retrospective review of 87 children with transient (n=37) or persistent congenital hyperinsulinism (CHI) (n=50) was conducted at the University Children’s Hospital Duesseldorf, Germany. Possible risk factors for neurodevelopmental sequelae due to hypoglycemia were analyzed with a focus on the first days after onset of disease.ResultsMedian age at follow-up was 7 years (IQR 8). Adverse neurodevelopmental outcome was seen in 34.5% (n=30) of all CHI patients. Fifteen had mildly abnormal neurodevelopment and 15 had a severe hypoglycemic brain injury. In univariate analysis, mildly abnormal neurodevelopment was associated with the diagnosis of persistent CHI (odds ratio (OR) 8.3; p=0.004) and higher birth weight (mean difference 1049 g; p&lt;0.001). Severe hypoglycemic brain injury was associated with the diagnosis of persistent CHI (OR 5.1; p=0.013), being born abroad (OR 18.3; p&lt;0.001) or in a lower-level maternity hospital (OR 4.8; p=0.039), and of note history of hypoglycemic seizures (OR 13.0; p=&lt;0.001), and a delay between first symptoms of hypoglycemia and first blood glucose measurement/initiation of treatment (OR 10.7; p&lt;0.001). Children with severe hypoglycemic brain injury had lower recorded blood glucose (mean difference -8.34 mg/dl; p=0.022) and higher birth weight than children with normal development (mean difference 829 g; p=0.012). In multivariate binary logistic regression models, lowest blood glucose &lt;20 mg/dl (OR 134.3; p=0.004), a delay between initial symptoms and first blood glucose measurement/initiation of treatment (OR 71.7; p=0.017) and hypoglycemic seizures (OR 12.9; p=0.008) were positively correlated with severe brain injury. Analysis showed that the odds for brain injury decreased by 15% (OR 0.85; p=0.035) if the blood glucose increased by one unit.ConclusionWhile some risk factors for adverse outcome in CHI are not influenceable, others like lowest recorded blood glucose values &lt;20 mg/dl, hypoglycemic seizures, and insufficiently—or even untreated hypoglycemia can be avoided. Future guidelines for management of neonatal hypoglycemia should address this by ensuring early identification and immediate treatment with appropriate escalation steps.

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Neonatal hypoglycemia affects up to 15% of all newborns. Despite the high prevalence there is no uniform definition of neonatal hypoglycemia, and existing guidelines differ significantly in terms of when and whom to screen for hypoglycemia, and where to set interventional thresholds and treatment goals. In this review, we discuss the difficulties to define hypoglycemia in neonates. Existing knowledge on different strategies to approach this problem will be reviewed with a focus on long-term neurodevelopmental outcome studies and results of interventional trials. Furthermore, we compare existing guidelines on the screening and management of neonatal hypoglycemia. We summarize that evidence-based knowledge about whom to screen, how to screen, and how to manage neonatal hypoglycemia is limited – particularly regarding operational thresholds (single values at which to intervene) and treatment goals (what blood glucose to aim for) to reliably prevent neurodevelopmental sequelae. These research gaps need to be addressed in future studies, systematically comparing different management strategies to progressively optimize the balance between prevention of neurodevelopmental sequelae and the burden of diagnostic or therapeutic procedures. Unfortunately, such studies are exceptionally challenging because they require large numbers of participants to be followed for years, as mild but relevant neurological consequences may not become apparent until mid-childhood or even later. Until there is clear, reproducible evidence on what blood glucose levels may be tolerated without negative impact, the operational threshold needs to include some safety margin to prevent potential long-term neurocognitive impairment from outweighing the short-term burden of hypoglycemia prevention during neonatal period.