Evidence of early impairment of parasympathetic reflexes in insulin dependent diabetics without autonomic symptoms.

Cardiovascular (CV) autonomic functions were assessed in 50 insulin-dependent diabetic patients and in 30 controls using a battery of autonomic tests: Valsalva Manoeuvre (VR), Deep Breathing (DB), Lying-to-Standing (LS), Sustained Handgrip (SHG) and Postural Hypotension (PH). The results were compared with those obtained from a study of cardiac resting adjustment to different static postures (quiet lying and standing). 10 diabetics with abnormal responses to the majority of tests were considered affected by Diabetic Autonomic Neuropathy (DAN); 15 with some abnormal of borderline responses were defined much less than Borderlines much greater than. The remaining 25 diabetics, while displaying lower values than the controls in parasympathetic tests, had much less than normal much greater than autonomic responses. The VR mean (+/- SD) value was 1.71 +/- 31 in much less than normal much greater than diabetics and 2.01 +/- 0.29 in controls (p less than 0.001); the DB mean value was 20.6 +/- 87 and 28 +/- 8.13 (p less than 0.001), and the LS mean value 1.16 +/- 0.12 and 1.33 +/- 0.18 (p less than 0.001) respectively. No significant differences were found in the sympathetic tests (SHG, PH). However Heart Rate (HR) adjustment of diabetics with normal CV responses to immobile standing (RR mean 783 +/- 136 ms) and lying (RR mean increment of 25 +/- 11%; p less than 0.001) was similar to that of controls who had a resting HR standing (RR mean 749 +/- 104 ms) and lying (RR mean 884 +/- 116 ms) with a mean increment of 20.2 +/- 10.9% (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)