Decrease heart rate variability but preserve postural blood pressure change in type 2 diabetes with microalbuminuria.
BACKGROUND
This study compares the cardiovascular autonomic function in type 2 diabetes with and without microalbuminuria, in order to identify the possible links between early nephropathy and diabetic autonomic neuropathy (DAN).


METHODS
Cardiovascular reflex tests were performed to determine the cardiovascular autonomic function. Thirty cases of type 2 diabetes with microalbuminuria were studied for evidence of DAN to compare with a normoalbuminuric group of 56 diabetic patients.


RESULTS
There was an increased prevalence of autonomic dysfunction in patients with microalbuminuria (63.3% in the microalbuminuria group vs. 40.0% in the normoalbuminuric controls, p = 0.001). These patients had lower heart rate variability during single breathing tests (6.9 +/- 4.3 vs. 9.6 +/- 3.6 beats/minute, p = 0.005), during 6 consecutive breathings (5.8 +/- 3.6 vs. 8.2 +/- 3.3 beats/minute, p = 0.005), after standing up (12.2 +/- 4.6 vs. 15.0 +/- 5.2 beats/ minute, p = 0.012), and during the Valsalva maneuver (11.3 +/- 3.5 vs. 13.2 +/- 3.6 beats/minute, p = 0.022). The heart rate variability with these stresses was revealed to be less favorable in subjects with microalbuminuria. However, blood pressure (BP) changes from the sitting to standing position were not significantly different for systolic BP (11.5 +/- 10.7 vs. 10.7 +/- 7.8 mmHg, p = 0.741) and diastolic BP (5.2 +/- 4.4 vs. 5.9 +/- 4.0 mmHg, p = 0.451) between the 2 groups.


CONCLUSIONS
Type 2 diabetic patients with microalbuminuria have diminished heart rate variability in response to deep breathing, change of position and the Valsalva maneuver, but they preserve BP response to postural change. Therefore, microalbuminuria seems to be associated with early DAN, but not with advanced DAN.
Chen
Harn-Shen
HS
Division of Endocrinology and Metabolism, Department of Medicine, Taipei Veterans General Hospital, Taiwan, ROC. chenhs@vghtpe.gov.tw
Wu
Tzu-En
TE
Jap
Tjin-Shing
TS
Lee
Shen-Hung
SH
Wang
Mei-Li
ML
Lu
Ron-A
RA
Chen
Ru-Lin
RL
Lin
Hong-Da
HD
D000368:Aged; D000419:Albuminuria / Q000503:physiopathology*; D001342:Autonomic Nervous System Diseases / Q000503:physiopathology; D001794:Blood Pressure; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D003929:Diabetic Neuropathies / Q000503:physiopathology; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D011187:Posture; D012018:Reflex; D013312:Stress, Physiological / Q000503:physiopathology