[Prospective study of cardiac autonomic neuropathy in diabetes mellitus]

For assessment of clinical and prognostic values of cardiac autonomic neuropathy, 53 patients with diabetes mellitus were followed-up for five years. Parasympathetic innervation was assessed by recording heart rate variability during deep breathing, Valsalva manoeuvre and lying-to-standing while sympathetic function was evaluated by measuring postural change in systolic blood pressure. During the follow-up period 1 of 23 diabetic patients died in group without signs of cardiac autonomic neuropathy whereas 2 of 13 diabetics and 10 of 17 diabetics deceased in groups with mild and definitive signs of cardiac autonomic neuropathy, respectively. At reinvestigation, the values of tests for parasympathetic impairment worsened or did not change significantly while improvement in these tests was only exceptionally observed in 40 diabetic patients. No significant change in values of test for sympathetic function was documented during the follow-up period suggesting that parasympathetic (vagal) impairment might precede the sympathetic dysfunction during development of autonomic neuropathy in diabetic patients. No correlation was observed between changes in cardiac autonomic neuropathy and alterations in distal somatic neuropathy (assessed by measurement of motor nerve conduction velocity in peroneal nerves) during the prospective study. Definitive cardiac autonomic neuropathy--as one of the late complications of diabetes mellitus--suggests poor prognosis in diabetic patients.