Autonomic function tests in non-insulin dependent diabetic patients and apparently healthy volunteers.

Traditionally accepted symptoms suggestive of autonomic neuropathy (ANP) were elicited in 65 non-insulin dependent diabetic patients attending a diabetic clinic and four autonomic function tests (AFTs) were performed in these diabetics and 60 non-diabetic healthy volunteers. Though 18 (27.6%) diabetics had symptoms of ANP, none of these symptoms were severe. AFTs were abnormal in 30 (46.2%) diabetics and 9 (15%) healthy volunteers. AFT abnormalities in diabetics were found more frequently than symptoms would suggest (21, i.e. 70% of the 30 diabetics did not have symptoms of ANP). There was poor correlation between symptoms of ANP and AFT abnormalities (only 9 of the 18 diabetics with symptoms of ANP had abnormal AFTs). Of the four AFTs performed, R-R variation was the commonest abnormality occurring in 17 of the 30 diabetics with abnormal AFTs. The prevalence of AFT abnormalities did not increase significantly with the duration of diabetes (chi 2 = 0.42; p = 0.8392), but increased significantly with the advancing age of the diabetics (chi 2 = 11.14; p less than 0.005). In healthy volunteers, the test values for standard deviation for R-R variation in deep breathing decreased significantly (p less than 0.05) with the advancing age of the subjects.