QTc and autonomic neuropathy in diabetes: effects of acute hyperglycaemia and n-3 PUFA.
OBJECTIVE
Autonomic function is also regulated by glycaemia and exerts a crucial role in the control of blood pressure and cardiac function. The disruption of this physiological mechanism impacts deeply on cardiovascular mortality in diabetes. We investigated the influence of autonomic dysfunction on QTc interval and on sympatho-vagal balance (LF/HF), in response to acute hyperglycaemia and to membrane electrical stabilization (n-3 PUFA).


RESULTS
Twenty-four type 2 diabetic patients, without (N-: n=13) or with (N+: n=11) autonomic neuropathy and 13 healthy subjects (C) underwent BP and ECG monitoring during a 24-h period and during a 2-h hyperglycaemic clamp. Delta QTc during the night was blunted in diabetics (0.5+/-2.5 vs. C: 2.9+/-2.5%, p=0.001), and Delta LF/HF was decreased in N+ (-2.8+/-38.2 vs. C=34.8+/-28.1%, p=0.02). During hyperglycaemia, QTc increased in C; LF/HF significantly increased in C and N-. A 6-month treatment with n-3 PUFA partially restored Delta LF/HF and Delta QTc (2.1+/-1.40, p=0.04 vs. basal) only in N-.


CONCLUSIONS
Hyperglycaemia increases QTc interval and sympathetic activity; electrical membrane stabilization improves autonomic function only in the absence of overt autonomic neuropathy. Strategies to prevent the disruption of autonomic function with newer approaches, other than just glucose control, should be implemented.
Santini
Vanina
V
Diabetes Centre, Department of Internal Medicine, University Tor Vergata, Viale Duilio Cambellotti 11, I-00133 Rome, Italy.
Ciampittiello
Giuseppina
G
Gigli
Fabrizio
F
Bracaglia
Daniela
D
Baroni
Alessandra
A
Cicconetti
Elena
E
Verri
Cristian
C
Gambardella
Sergio
S
Frontoni
Simona
S
D001341:Autonomic Nervous System / Q000502:physiology*; D001342:Autonomic Nervous System Diseases / Q000503:physiopathology*; D001794:Blood Pressure / Q000502:physiology; D048909:Diabetes Complications; D003924:Diabetes Mellitus, Type 2; D003929:Diabetic Neuropathies / Q000503:physiopathology*; D004562:Electrocardiography; D015525:Fatty Acids, Omega-3 / Q000494:pharmacology*; D005260:Female; D015309:Glucose Clamp Technique; D006334:Heart Function Tests; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D006943:Hyperglycemia / Q000150:complications*; D008297:Male; D008875:Middle Aged
D015525:Fatty Acids, Omega-3