Correlation between cardiovascular autonomic neuropathy and distal symmetric polyneuropathy in type 2 diabetes

Objective: To study whether HR variability might be impaired before the clinician becomes aware for the presence of PNP and to define the correlation between CAN and PNP in type 2 diabetes. Patients and method: 212 type 2 diabetic patients were examined by 5 autonomic reflex tests: 1.deep breathing test 2.Valsalva test; 3.heart rate response during stand test; 4.orthostatic blood pressure response; 5.dyastolic blood pressure response during isometric exercise. PNP was diagnosed Michigan screening test. Results: More than half the patients without evidence of PNP were diagnosed as subclinical CAN and almost 3/4 of patients with evidence of PNP had autonomic impairment. We found a good correlation between CAN and PNP (p=0.0017). Conclusion: 1. CAN may develop first and independent from PNP in type 2 diabetes. 2. Evidence of one type of neuropathy increases the risk for the other type of neuropathy. 3. Periodical survey of neurological involvement should include autonomic function testing besides the well known practice of screening for somatic neuropathy in diabetes.