Symptoms of hypoglycaemia in children and adolescents with type 1 diabetes mellitus

Introduction and methods: The occurrence of hypoglycaemic symptoms in childhood was evaluated in 23 adolescents with insulin dependent diabetes mellitus by inducing mild hypoglycaemia in the presence of their parents. The procedure was approved by the local Ethics Committee. The objektive symptoms of hypoglycaemia were analysed by a symptom score for autonomic and neuroglycopenic symptoms of hypoglycaemia. Glucose levels were determined using a standard hexokinase method and catecholamine levels were measured radioenzymatically. A radioimmunoassay was used to estimate isoprenaline-induced cAMP levels in lymphocytes. Results: Only 34,8% of the patients had the typical early autonomic symptoms of hypoglycaemia, whereas 65,2% recognised neuroglycopenic symptoms of hypoglycaemia only or no symptoms at all. The occurrence of early autonomic symptoms decreased with the duration of diabetes whereas no change was found for neuroglycopenic symptoms. Only two patients with recurrent episodes of nocturnal hypoglycaemia but 9 of the parents recognised hypoglycaemia too late or not at all. Patients with recurrent episodes of anamnestic hypogly caemia showed significantly diminished hypoglycaemia-induced adrenaline release and cAMP accumulation compared to adolescents without hypoglycaemia. Patients with neuroglycopenic symptoms of hypoglycaemia had significantly diminished cAMP accumulation compared to those with autonomic symptoms. Conclusion: Recurrent episodes of anamnestic hypoglycaemia are a main cause for frequent occurrence of hypoglycaemia unawareness in childhood diabetes mellitus. The desensitisation of adrenergic signal transduction may be an additional factor in the pathogenesis of hypoglycaemia unawareness. The parents of diabetic children and adolescents should regularly be trained with respect to the detection of hypoglycaemia symptoms.