Cardiac autonomic nerve function and insulin sensitivity in obese subjects.
OBJECTIVE
To investigate whether obesity influences cardiac autonomic nerve function.


METHODS
Comparing two groups of subjects with different degrees of obesity to normal weight controls.


METHODS
19 healthy controls (mean age 33 y, BMI 21.7 +/- 0.2 kg/m2) and 17 obese non-diabetic subjects (mean age 39 y, BMI 33.7 +/- 1.8 kg/m2).


METHODS
Insulin sensitivity was calculated by an oral glucose tolerance test. Autonomic nerve function was evaluated by analysing the variation of the heart frequency at rest (coefficient variation of R-R intervals, REST 1), during deep respiration, at a Valsalva maneuver (longest/shortest R-R interval during inspiration hold) and by the Ewing test (ratio between the 30th and 15th R-R interval after reaching up-right position).


RESULTS
The obese showed a lower insulin sensitivity than healthy controls (3.09 vs 4.60 mg x l2/mmol x mU x min, P < 0.001). Their variation in heart frequency was reduced (REST 1: 1.95 vs 2.9, P < 0.01, Valsalva: 1.30 vs 1.52 and Ewing test: 1.03 vs 1.14, P < 0.05). However, patients with moderate (BMI 31.7 kg/m2) or severe obesity (39.0 kg/m2) with identical insulin sensitivity had no significant difference in autonomic nerve function. Except for the Ewing test all measured parameters for the evaluation of cardiac autonomic nerve function correlated with the degree of diminished insulin sensitivity (REST 1: r = 0.475, P < 0.001).


CONCLUSIONS
Moderate obesity with significantly decreased insulin sensitivity is associated with impaired cardiac autonomic nerve function.
Department of Internal Medicine II, University of Munich, Klinikum Grosshadern, Germany.
W O
WO
Richter
H C
HC
Geiss
S
S
Aleksic
P
P
Schwandt
D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D005260:Female; D005951:Glucose Tolerance Test; D006321:Heart / Q000294:innervation*; D006339:Heart Rate; D006801:Humans; D007328:Insulin / Q000097:blood / Q000494:pharmacology*; D008297:Male; D009765:Obesity / Q000503:physiopathology*; D011187:Posture; D012119:Respiration; D014636:Valsalva Maneuver
D001786:Blood Glucose; D007328:Insulin