Electrocardiographic alterations during hyperinsulinemic hypoglycemia in healthy subjects.
BACKGROUND
We evaluated the arrhythmogenic potential of hypoglycemia by studying electrocardiographic (ECG) changes in response to hyperinsulinemic hypoglycemia and associated sympathoadrenal counterregulatory responses in healthy subjects.


METHODS
The study population consisted of 18 subjects, aged 30-40 years. Five-minute ECG recordings and blood samplings were performed at baseline and during the euglycemic and hypoglycemic hyperinsulinemic clamp studies. PR, QT, and QTc intervals of electrocardiogram and ECG morphology were assessed from signal-averaged ECG.


RESULTS
Although cardiac beat interval remained unchanged, PR interval decreased (P < 0.01) and QTc interval (P < 0.001) increased in response to hyperinsulinemic hypoglycemia. Concomitant morphological alterations consisted of slight increases in R-wave amplitude and area (P < 0.01 for both), significant decreases in T-wave amplitude and area (P < 0.001 for both), and moderate ST depression (P < 0.001). Counterregulatory norepinephrine response correlated with amplification of the R wave (r =-0.620, P < 0.05) and epinephrine response correlated with flattening of the T wave (r =-0.508, P < 0.05).


CONCLUSIONS
Hyperinsulinemic hypoglycemia with consequent sympathetic humoral activation is associated with several ECG alterations in atrioventricular conduction, ventricular depolarization, and ventricular repolarization. Such alterations in cardiac electrical function may be of importance in provoking severe arrhythmias and "dead-in-bed" syndrome in diabetic patients with unrecognized hypoglycemic episodes.
Laitinen
Tomi
T
Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital and University of Kuopio, Kuopio, Finland. Tomi.Laitinen@kuh.fi
Lyyra-Laitinen
Tiina
T
Huopio
Hanna
H
Vauhkonen
Ilkka
I
Halonen
Toivo
T
Hartikainen
Juha
J
Niskanen
Leo
L
Laakso
Markku
M
D000328:Adult; D000704:Analysis of Variance; D015331:Cohort Studies; D004562:Electrocardiography; D005260:Female; D005947:Glucose / Q000494:pharmacology; D015309:Glucose Clamp Technique; D006329:Heart Conduction System / Q000502:physiology*; D006801:Humans; D006946:Hyperinsulinism / Q000150:complications*; D007003:Hypoglycemia / Q000150:complications*; D007262:Infusions, Intravenous; D007328:Insulin / Q000494:pharmacology; D008297:Male; D011336:Probability; D012016:Reference Values; D018709:Statistics, Nonparametric
D007328:Insulin; D005947:Glucose