title: Weak relationship between symptom perception and objective hypoglycaemia-induced changes of autonomic function in hypoglycaemia unawareness in diabetes.
abstract: To assess the relationship between symptom perception and neurophysiological characteristics in hypoglycaemia unawareness, we investigated the awareness of symptoms, objective changes of autonomic function and counter-regulatory neuroendocrine responses to hypoglycaemia in intensively treated type I (insulin-dependent) diabetic patients with different degrees of hypoglycaemia unawareness. Hypoglycaemia (venous plasma glucose below 2.2 mmol/l) was induced with an intravenous insulin bolus in subjects with a history of repeated severe hypoglycaemia and hypoglycaemia unawareness (n = 10) and in a comparable group with good awareness of hypoglycaemia (n = 8). Autonomic symptoms, selected parameters of autonomic function and counter-regulatory hormones were assessed serially. Although hypoglycaemia was more pronounced in unaware patients (1.6 vs 2.0 mmol/l, P = 0.05), their induced adrenaline response was markedly impaired (delta adrenaline: 1.25+/-1.10 vs 2.55+/-1.46 nmol/l, P = 0.05). Astonishingly, differences between both patient groups in the course of autonomic function changes did not reach the level of significance (P = 0.35-0.92), although the unaware group reported markedly fewer autonomic symptoms, both neurogenic (P = 0.001) and neuroglycopenic (P = 0.04) than the aware group. This study indicates that in hypoglycaemia unawareness even extensive changes in autonomic function are not sufficient for the perception of hypoglycaemia and confirms that the central nervous system plays an important role in the awareness of hypoglycaemia.
authors.affiliation: Department of Biomedical Engineering and Physics, University of Vienna, Allgemeines Krankenhaus, Vienna, Austria.
authors.forename: K
authors.initials: K
authors.lastname: Howorka
authors.forename: G
authors.initials: G
authors.lastname: Heger
authors.forename: A
authors.initials: A
authors.lastname: Schabmann
authors.forename: F
authors.initials: F
authors.lastname: Skrabal
authors.forename: J
authors.initials: J
authors.lastname: Pumprla
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001342:Autonomic Nervous System Diseases / Q000209:etiology*; D001786:Blood Glucose / Q000032:analysis; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000150:complications / Q000503:physiopathology; D004837:Epinephrine / Q000097:blood; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007003:Hypoglycemia / Q000150:complications* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010465:Perception
chemical_list: D001786:Blood Glucose; D004837:Epinephrine