The objective of this study was to investigate the effects of diabetic distal peripheral neuropathy on static posture. From a clinical perspective, this research was designed to determ ine if the diabetic population w ith neuropathy presents sw ay characteristics that indicate a reduced ability to control posture that m ight possibly lead to an increased likelihood for falls. From a basic knowledge perspective, the unique neurophysiological m odel that the diabetic individuals w ith neuropathy represent perm itted the estimation of the relative contribution of the som atosensory system to the overall control of posture.

Seventeen diabetic subjects with significant neuropathy (ages 40 to 70) were recruited for this study. These neuropathic subjects were matched based on gender, age, weight and height w ith 17 diabetic individuals w ithout significant neuropathy and 17 nondiabetic subjects w ith normal cutaneous sensation. The subjects in the two diabetic groups were also matched based on duration of diabetes. All participants underw ent an extensive medical screening consisting of somatosensory, functional, visual, vestibular and motor tests. The goal of this screening was to obtain three groups of matched subjects so that the effects of diabetes and diabetic sensory neuropathy on posture could be analyzed separately.

Each subject was tested for static postural stability under nine "sensory" conditions where head position, vision and som atosensory conditions were manipulated. Postural stability was quantified through center of pressure data collected w hile the subject stood quietly on a force platform.

Compared to the diabetic subjects w ithout neuropathy and the nondiabetic subjects, the neuropathic group exhibited significantly greater difficulty m aintaining a stable stance position (as indicated by greater excursion and range of the center of pressure signal) for all nine sensory conditions (p < .01). In general, no statistically significant differences (p > .05) were found for the postural characteristics of the nonneuropathic diabetic subjects and the nondiabetic group. W hile diabetes per se did not influence posture, these results are strongly indicative of the detrim ental effects of neuropathy on the control of balance.

Most importantly, this stu d y dem onstrated that the somatosensory system accounted for at least 40% of the total control of posture, m aking this sensory system the most important contributor to balance.