[Cardiovascular effects of autonomic neuropathy in insulin-dependent diabetes mellitus]

The present study was designed to evaluate whether autonomic diabetic neuropathy is a marker of severe cardiovascular disease. We recruited three groups of 12 patients each with the same age, sex and body weight distribution: Group DAN + (diabetics with neuropathy), Group DAN- (diabetics without neuropathy) and Group C (healthy control group). The patients underwent two-dimensional color Doppler echocardiography and maximal electrocardiographic exercise test by cycloergometer (multistage program with 25 W increments 3 min steps). Cardiovascular autonomic function was evaluated by Ewing's tests (heart rate and blood pressure measurement during lying to standing, deep breathing, handgrip isometric stress test and Valsalva manoeuvre). Heart rate and blood pressure proved to be significantly higher in the Group DAN+, than in the other groups, either at baseline or during stress test. Only 33% of DAN+ patients proved to reach 100 W during stress test, compared to 82% of DAN- and 87% of control subjects. No DAN+ patients reached 125 W, compared with 45% of DAN- and 58% of Group C patients. Echocardiographic examination showed normal left ventricular systolic function in all groups, without any significant difference in ventricular dimensions, and impaired left ventricular diastolic function in DAN+ patients, compared to Group C subjects (peak E 66.75 +/- 8.36 vs 73.49 +/- 12.53 cm/s; peak A 72.1 +/- 13.42 vs 59.75 +/- 13.26 cm/s; E/A 0.84 +/- 0.21 vs 1.38 +/- 0.15 and isovolumetric relaxation time 101 +/- 21 vs 70 +/- 17 ms). Our data suggest that diabetic autonomic neuropathy is a marker of reduced exercise tolerance and of diastolic left ventricular dysfunction.