title: Reversal of hypoglycemia unawareness in a long-term type 1 diabetic patient by improvement of beta-adrenergic sensitivity after prevention of hypoglycemia.
abstract: The purpose of this study was to assess the effect of strict avoidance of hypoglycemia on beta-adrenergic sensitivity in a type 1 diabetic patient with hypoglycemia unawareness and a diabetes duration of 55 yr. beta-Adrenergic sensitivity was determined by an isoproterenol test and was expressed as the lowest dose of isoproterenol that increases the heart rate by 25 beats/min (IC25). Plasma epinephrine and symptom responses to hypoglycemia were determined during a 3-h hypoglycemic (3 mmol/L) clamp. Initially, the patient had a near-normal counterregulatory plasma epinephrine response to hypoglycemia but reduced beta-adrenergic sensitivity (IC25, 2 microg) compared to 10 hypoglycemia aware, type 1 diabetic patients (0.65 +/- 0.14 microg) and 10 normal control subjects (1.13 +/- 0.21 microg). After 1 yr of strict avoidance of blood glucose levels below 4 mmol/L, the IC25 decreased to 0.25 microg, reflecting improved beta-adrenergic sensitivity. In conclusion, the reduced beta-adrenergic sensitivity in this patient was probably the reason for hypoglycemia unawareness and was reversed by strict avoidance of hypoglycemia.
authors.affiliation: Department IV Internal Medicine, Endocrinology, and Pathobiochemistry, University of Tubingen, Germany. andreas.fritsche@med.unituebingen.de
authors.forename: A
authors.initials: A
authors.lastname: Fritsche
authors.forename: M
authors.initials: M
authors.lastname: Stumvoll
authors.forename: H U
authors.initials: HU
authors.lastname: Häring
authors.forename: J E
authors.initials: JE
authors.lastname: Gerich
mesh_terms: D000318:Adrenergic beta-Agonists; D000328:Adult; D001364:Awareness; D001786:Blood Glucose / Q000032:analysis; D002908:Chronic Disease; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000503:physiopathology; D004837:Epinephrine / Q000097:blood; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007003:Hypoglycemia / Q000097:blood / Q000517:prevention & control* / Q000523:psychology*; D007545:Isoproterenol; D008297:Male; D008875:Middle Aged; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D012016:Reference Values
chemical_list: D000318:Adrenergic beta-Agonists; D001786:Blood Glucose; D011943:Receptors, Adrenergic, beta; D007545:Isoproterenol; D004837:Epinephrine