REVIEW What’ s new in metabolic and genetic hypoglycaemias: diagnosis and management Vassili Valayannopoulos & Stéphane Romano & Karine Mention & Anne Vassault & Daniel Rabier & Michel Polak & Jean-Jacques Robert & Yves de Keyzer & Pascale de Lonlay Received: 11 April 2007 / Accepted: 23 August 2007 / Published online: 3 October 2007 # Springer-Verlag 2007 Abstract Hypoglycaemia in children can be a life-threatening situation that needs to be assessed rigorously in order to treat efficiently and avoid relapse that can be responsible for cerebral damage. The diagnosis of impairment in glucose homeostasis requires the knowledge of the mechanisms regulating blood glucose concentration. The clinical history and presentation, when available, especially the timing of hypoglycaemia with respect to the last meal and some simple clinical and biological tests may allow diagnosing the vast majority of patients presenting with hypoglycaemia. Recently, new metabolic and endocrinologic genetic causes of hypo- glycaemia have been identified that may give new insight to the complex mechanisms of glucose regulation and thus contribute to the discovery of new genes regulating glucose homeostasis. New diagnostic tests such as the 18-fluoro-Dopa PET-scan have also been recently developed. Keywords Hypoglycaemia . Hyperinsulinism . Metabolic . Diagnosis . Children Abbreviations ATP: Adenosine triphosphate BWS: Beckwith-Wiedemann syndrome CDG: Congenital disorders of glycosylation FAO: Fatty acid oxidation FBS: Fanconi-Bickel syndrome GDH: Glutamate dehydrogenase GH: Growth hormone GK: Glucokinase GTP: Guanosine triphosphate HI: Hyperinsulinism HIHA: Hyperinsulinism-hyperammoniemia syndrome IGF1: Insuline-like growth factor 1 MCT: Mean chain triglycerides PET: Positron emission tomography SCHAD: Short chain 3-hydroxyacyl-CoA dehydrogenase deficiency TBG: Thyroxin-binding globulin Introduction Hypoglycaemia, defined by a glucose plasma level below 3 mmol/l (55 mg/dl) in children and below 2 mmol/l (1st Eur J Pediatr (2008) 167:257–265 DOI 10.1007/s00431-007-0600-2 V. Valayannopoulos (*) : S. Romano Metabolic Department and Reference Centre for Metabolic Diseases, Necker-Enfants Malades Hospital, 149, Rue des Sèvres, 75015 Paris, France e-mail: vassili.valaya@nck.aphp.fr K. Mention Reference Centre for Metabolic Diseases, Jeanne de Flandre Hospital, Lille, France A. Vassault : D. Rabier Biochemistry Laboratory, Necker-Enfants Malades Hospital, Paris, France M. Polak : J.-J. Robert Endocrinology Department, Necker-Enfants Malades Hospital, Paris, France Y. d. Keyzer INSERM U 781, Necker-Enfants Malades Hospital, Paris, France P. d. Lonlay Metabolic Department and Reference Center for Metabolic Diseases and INSERM U 781, Necker-Enfants Malades Hospital, 149, Rue des Sèvres, 75015 Paris, France