Correlations Among Autonomic, Sensory, and Motor Neural Function Tests in Untreated Non-insulin-dependent Diabetic Individuals

Abstract

A well-defined group of untreated non-insulin-dependent (NIDD) subjects were evaluated to determine whether involvement of neural function measurements is generalized and symmetrical and to compare the autonomic, sensory, and motor neural measurements. After age adjustment, the sensory and motor neural function measurements were significantly slower in the diabetic group than in normal subjects (P < 0.01). Similarly, the autonomic nervous system function measurements were also abnormal in the NIDD group (P < 0.01). Further analysis revealed that each of the specific measurements–median motor nerve conduction velocity (NCV, P < 0.005), peroneal motor NCV (P < 0.005), median sensory NCV (P < 0.005), dark-adapted pupil size after muscarinic blockade (P < 0.02), pupillary latency time (P < 0.02), and RR-variation after beta adrenergic blockade (P < 0.001)—was significantly less by analysis of covariance after age adjustment in the NIDD group than in normal subjects. Thus, there was evidence of motor and sensory neural impairment in the upper and lower extremities as well as evidence of impairment of the reflex arcs involving the parasympathetic nerves to the heart and eye and the sympathetic nerves to the iris. Further analysis revealed that right and left NCV were correlated (P < 0.01), as were the median motor and median sensory NCV (P < 0.01), the median motor and peroneal motor NCV (P < 0.001), and the peroneal motor and median sensory NCV (P < 0.001). Thus, there was evidence of symmetrical upper and lower limb, as well as motor and sensory proportional involvement of large nerve fiber NCV in this group of NIDD subjects. Within the autonomic nerve reflex arcs that were tested, the studies showed that there was correlation between measures assessing the reflex arcs involving the parasympathetic nervous system (PNS) to the heart and iris (P < 0.01). However, the measure assessing the sympathetic nervous system (SNS) reflex arc to the iris did not correlate significantly with either of the measures assessing PNS reflexes. Overall, measurements of sensory and motor NCV were correlated with the results of the autonomic nervous system (ANS) tests (P < 0.05). Thus, in a group of untreated NIDD men, age-adjusted measures of SNS, motor (MNS), and ANS function were reduced and there was a correlation between the measures of sensory and motor nerve tests and those of ANS function.