Abnormal baroreceptor-cardiac reflex sensitivity is not detected by conventional tests of autonomic function in patients with insulin-dependent diabetes mellitus.
1. Autonomic neuropathy is a common complication of diabetes mellitus and is a major risk factor for sudden death. 2. A group of 30 patients with insulin-dependent diabetes mellitus and 30 age-, sex- and blood pressure-matched control subjects underwent traditional tests of autonomic function. Resting supine R-R interval and systolic blood pressure variability were assessed using spectral analysis methods. In addition, we assessed the baroreceptor-cardiac reflex from the linear relation of the change in R-R interval to the increasing systolic blood pressure measured non-invasively with the Finapres monitor during phase 4 of the Valsalva manoeuvre and from resting heart rate and systolic blood pressure power spectra. 3. Whereas standard tests of autonomic function revealed no differences between patients with insulin-dependent diabetes mellitus and control subjects, there was a significant reduction in power spectral density of heart rate variability around the high-frequency region (125.2 +/- 112.9 versus 459.3 +/- 189.8 ms2, mean +/- SD). Furthermore, reductions in baroreflex sensitivity calculated from the Valsalva manoeuvre were detected in diabetics compared with controls (3.3 +/- 1.6 versus 9.5 +/- 2.5 ms/mmHg, mean +/- SD, P < 0.00001). There were significant relations between impairment of the baroreflex and duration of diabetes (P < 0.001) and poor diabetic control (P < 0.05). 4. In summary, autonomic dysfunction occurs much more frequently in diabetic patients than conventional tests would suggest. Abnormal baroreceptor-cardiac reflex sensitivity in patients with insulin-dependent diabetes mellitus may in part be explained by abnormal parasympathetic function. This unrecognized abnormality may have a role in the increased incidence of sudden death seen in young diabetic subjects.
Weston
P J
PJ
Department of Medicine and Therapeutics, Leicester Royal Infirmary, U.K.
James
M A
MA
Panerai
R
R
McNally
P G
PG
Potter
J F
JF
Thurston
H
H
Swales
J D
JD
D000328:Adult; D000375:Aging / Q000502:physiology; D001341:Autonomic Nervous System / Q000503:physiopathology*; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000503:physiopathology*; D006442:Glycated Hemoglobin / Q000032:analysis; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D013997:Time Factors; D014636:Valsalva Maneuver
D006442:Glycated Hemoglobin