Effect of essential hypertension on cardiac autonomic function in type 2 diabetic patients.
OBJECTIVE
The aim of this study was to examine the effects of essential hypertension on cardiac autonomic function in type 2 diabetic patients.


BACKGROUND
Hypertension is common in type 2 diabetic patients and is associated with a high mortality. However, the combined effects of type 2 diabetes and essential hypertension on cardiac autonomic function have not been fully elucidated.


METHODS
Thirty-three patients with type 2 diabetes were assigned to a hypertensive diabetic group (n = 15; age: 56 +/- 8 years, mean +/- SD) or an age-matched normotensive diabetic group (n = 18, 56 +/- 6 years). Cardiac autonomic function was assessed by baroreflex sensitivity (BRS), heart rate variability (HRV), plasma norepinephrine concentration and cardiac 123I-metaiodobenzylguanidine (MIBG) scintigraphic findings.


RESULTS
Baroreflex sensitivity was lower in the hypertensive diabetic group than it was in the normotensive diabetic group (p < 0.05). The early and delayed myocardial uptake of 123I-MIBG was lower (p < 0.01 and p < 0.05, respectively), and the percent washout rate of 123I-MIBG was higher (p < 0.05) in the hypertensive diabetic group. However, the high frequency (HF) power and the ratio of low frequency (LF) power to HF power (LF/HF) of HRV and plasma norepinephrine concentration were not significantly different. The homeostasis model assessment index was higher in the hypertensive diabetic group than it was in the normotensive diabetic group (p < 0.01).


CONCLUSIONS
Our results indicate that essential hypertension acts synergistically with type 2 diabetes to depress cardiac reflex vagal and sympathetic function, and the results also suggest that insulin resistance may play a pathogenic role in these processes.
Takahashi
N
N
Department of Internal Medicine I, School of Medicine, Oita Medical University, Japan. takanao@oita-med.ac.jp
Nakagawa
M
M
Saikawa
T
T
Ooie
T
T
Yufu
K
K
Shigematsu
S
S
Hara
M
M
Sakino
H
H
Katsuragi
I
I
Okeda
T
T
Yoshimatsu
H
H
Sakata
T
T
D019797:3-Iodobenzylguanidine; D001341:Autonomic Nervous System / Q000503:physiopathology*; D017704:Baroreflex / Q000502:physiology; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D003925:Diabetic Angiopathies / Q000503:physiopathology*; D005260:Female; D006321:Heart / Q000294:innervation*; D006334:Heart Function Tests; D006339:Heart Rate; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D007333:Insulin Resistance / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D019275:Radiopharmaceuticals
D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine; D009638:Norepinephrine