Abnormalities in gait have an effect on patients beyond simple functional impairments. For example, Vileikyte et al. demonstrated that unsteadiness in gait was the strongest association with symptoms of depression in patients with diabetes [
34]. Furthermore, both mood and cognition may alter the relationship between diabetes and gait [
35].
People with diabetic neuropathy are at far greater risk of falling than those with intact sensation [
36,
37]. That most falls occur during locomotion [
36,
38] suggests that these patients may have difficulty maintaining dynamic stability while walking. In one study these patients showed greater deviation of their central mass from the centre of pressure during staircase and level walking [
39]. It has been suggested that sensory feedback may play a pivotal role in smoothing unintended irregularities that occur during unperturbed movements [
40] and in adjusting step-to-step limb trajectories to maintain balance during locomotion [
41]. In a study assessing autonomic function in relation to gait, people with diabetes took additional steps when walking in a linear path and during turns [
30]. Reduced walking speed, cadence and step length and fewer acceleration patterns have been noted in subjects with diabetic neuropathy [
32]. To our knowledge only one previous non-interventional study has assessed painful diabetic neuropathy and gait [
42]. The authors of this study concluded that people with painful diabetic neuropathy had greater variation in step length and step velocity but also tended to walk more [
42]. The painful diabetic neuropathy group also self-reported an increased number of falls with subsequent hospitalisations for injuries sustained, as well as a greater fear of falling [
42]. However, the method used to analyse gait in this study was a portable device attached to the patient; thus, the complexities of alterations in gait strategy in patients with painful diabetic neuropathy were not fully elucidated [
42]. Furthermore, the authors did not investigate any associations/relationships between painful diabetic neuropathy and quality of life and depression, despite the patients report this increased fear of falling [
42]. Interestingly, in another study, intervention with pregabalin in painful diabetic neuropathy did not improve gait stability of the patients; rather, it caused increasing variability in gait speed and step length [
43], possibly reflecting a higher risk of falling.
Individuals with DPN walk slower than age-matched healthy controls [
32,
44]. Dingwell et al. [
45] and Menz et al. [
32] demonstrated that those with greater DPN-related loss of plantar cutaneous sensation tended to walk with a slower preferred walking speed. However, increases in gait variability are linked to reductions in self-selected walking speed rather than sensory loss per se [
44]. Gait speed is positively correlated to survival advantage in the aged population [
46]. Presence of neuropathy has been shown to be an independent risk factor for death among patients with diabetes [
47].
Diabetic neuropathy is a recognised risk factor for diabetic foot ulceration [
6,
48,
49], and patients who develop diabetic foot ulceration are at increased risk of amputation [
50,
51]. Foot amputation is usually the sequela of a cascade of events, including the development of neuropathy, microangiopathy and vascular disease and abnormal plantar pressures and gait, all of which lead to foot ulcers [
52]. Once ulceration is present, the gait may alter further [
53], leading to a self-perpetuating situation of ulcer formation and lack of healing.
There are large variations in the results of studies addressing these aspects of DPN due to the heterogeneous population and small numbers of subjects enrolled.