Table 2.

Study characteristics on the impairments of gait performance's studies.

Author	Sample size	Age	Groups	Examined variables	Procedure	Results and conclusion
Allet et al. (2009) [34]	45	Not stated	DPN (15) DM without DPN (15) Control (15)	Temporal and spatial gait parameters Stride-to-stride variability	Gait is assessed on three different surfaces (tar, grass, and stones) with a Physilog1 system (BioAGM, CH), consisting of accelerometers and gyroscopes.	Gait parameters of DPN were differed significantly from healthy controls. Post hoc analysis revealed a significant difference between healthy individuals and patients with neuropathy and between healthy individuals and patients without neuropathy.
Allet et al. (2012) [35]	33	50–85	DPN (21) Control (12)	Gait analysis: (i) gait speed and efficiency (step-width-to-step-length ratio)	An optoelectronic camera system measured kinematic data.	Hip adduction rate torque development (RTD) and ankle inversion RTD predicted 54% of gait speed, with the former predicting the majority (44%). Ankle inversion RTD was the only significant predictor of gait efficiency, which accounted for 46% of its variability.
Brown et al. (2014) [36]	80	Not stated	DPN (20) DM without DPN (33) Control (27)	Kinematics Kinetics	VICON (motion analysis).	DM and DPN group showed significantly reduced peak torques at the ankle and knee.
Camargo et al. (2015) [37]	60	Not stated	DPN (30) Control (30)	Temporal and spatial gait parameters	Measuring  the time to walk a set distance during self-selected and maximal walking speeds.	Temporal-spatial gait, functional mobility, balance performance, and ankle muscle strength were affected in DPN group.
Chiles et al. (2014) [38]	983	>65	DM with and without DPN (126) Impaired fasting glucose (107) Control (750)	Gait speed	Short Physical Performance Battery (SPPB) by usual walking speed test (m/s).	DPN group showed lower walking speed.
Courtemanche et al. (1996) [39]	19		DPN (12) Control (7)	Gait	Walking task was performed on a nonslippery steel-covered pathway 8 m long.	For the walking task, DPN group had a smaller cycle amplitude, cycle speed, and single support time compared to the control group. Also, reaction times while walking were higher for DPN group than for control subjects. The increased attentional demands in gait for the DPN group, along with their more conservative gait pattern, suggest that a lack of proprioception from the legs affects the control of gait.
Dingwell et al. (1999) [14]	51	40–70	DPN (17) DM without DPN (17) Control (17)	Kinematic	Subjects walked on a motorized treadmill at a constant speed of 1 m/s.	DPN group did not demonstrate significantly greater variability than other groups.
de Mettelinge et al. (2013) [40]	101	>60	DPN (28) DM without DPN (28) Control (45)	Temporal and spatial gait parameters	Portable electronic GAITRite walkway system.	Compared with controls, older adults with diabetes walked slower, took shorter strides during all walking conditions, and showed more gait variability.
Fortaleza et al. (2014) [41]	41	Not stated	DPN (18) Control (23)	Gait stability: (1) gait speed; (2) percentage of time in double and single stance	Analyzed with an aropodometer by walking with EO, EC, EO, and narrow BOS.	DPN group showed lower gait speed, longer double stance time, and shorter single stance time in the three conditions.
Katoulis et al. (1997) [42]	60		DPN (20) DM without DPN (20) Control (20)	Gait parameters: (1) walking speed; (2) stance phase duration; (3) joint angles and moment arms for the ankle, knee, and hip joints in both sagittal and frontal planes; (4) the components of the ground reaction force (GRF) vector; (5) the ankle, knee, and hip joint moments originating from the GRF vector in both planes	Vifor (video force) system (LIC Orthopaedics, Stockholm, Sweden).	Walking speed was significantly slower in the DN group compared with the two control groups. The maximum knee joint angle was smaller in the sagittal plane for the DPN group compared with the control group values. The maximum value of the vertical component of GRF was found to be higher in the two control groups compared with the DPN group. The maximum value of the anteroposterior forces was also found to be higher in the control group compared with the DPN group.
Lalli et al. (2013) [43]	86	Not stated	DPN without pain (20) DPN with pain (22) DM (20) Control (24)	Gait parameters (variability of step length and step velocity)	Collection of GaitMeter data was performed during a single 10–20-minute session.	DPN group had greater variability of step length and step velocity, except for DM and control group. DPN group with pain contributes to gait variability, potentially contributing to the risk of falling in DM patients.
Manor et al. (2008) [44]	24	Not stated	DPN (12) Control (12)	Kinematic Gait variability	Two-dimensional sagittal plane kinematics were acquired (60 Hz) using single camera motion capture.	DPN group walked slower than the control group.
Martinelli et al. (2013) [45]	52	Not stated	DPN (25) Control (27)	Temporal and spatial gait parameters	Electronic baropodometry treadmill with walk on the treadmill (8.0 m) at her/his habitual self-selected speed.	DPN group showed impairment of gait, with a smaller stride and length speed of the cycle, and increased the duration of support time.
Najafi et al. (2013) [46]	20	>18	DPN (10) Control (10)	Temporal and spatial gait parameters	A validated system of body-worn sensors was used to extract spatiotemporal gait parameters.	Gait alteration in DPN group is most pronounced while walking barefoot over longer distances and that footwear may improve gait steadiness in patients with DPN.
Paul et al. (2009) [47]	30	65–75	DPN (15) DM without DPN (15)	Gait parameters: (1) step length; (2) duration duration of single and double support; (3) gait velocity; (4) cadence	GAITRite system.	Greater step length, lower single support time, higher double support time, slower gait velocity, and lower cadence in cognitive and motor task in DPN group compared with DM without DPN group.
Raspovic (2013) [48]	40	Not stated	DPN with foot ulcer history (10) DPN with no foot ulcer history (10) DM without DPN and ulcer history (10) Control (10)	Kinetic Kinematic	Vicon 512 Motion Analysis System. A force plate.	Gait alterations in people with clinically severe DPN and related plantar foot ulcer history.
Richardson et al. (2004) [49]	24	50–85	DPN (12) Control (12)	Gait performance: (1) step width; (2) step width variability; (3) step-width range; (4) step width-to-step length ratio; (5) step time; (6) step time variability; (7) step length; (8) step speed	Subjects placed in a safety harness that was attached by climbing rope to an overhead track and, then, walking in a SE (normal surface and lighting) and CE (irregular surface and low lighting).	DPN group demonstrated significant increases in step width, increased step-width variability, increased step-width range, increased step width-to-step length ratio, increased step time, increased step time variability, and decreased step length and speed in CE demonstrated a slower, wider-based, and more variable gait compared to SE.
Sawacha et al. (2009) [28]	67	Not stated	DPN (26) DM without DPN (21) Control (20)	Kinetic and kinematic gait	BTS motion capture system.	Altered gait was found in diabetic patients irrespective of polyneuropathy.
Savelberg et al. (2010) [50]	28	Not stated	DPN (8) DM without DPN (10) Control (10)	Gait velocity Kinematics	Body positions in the sagittal plane were recorded using a 2D digital optical recording system, which consisted of a 25 Hz interlaced digital video camera (50 frames/s).	Independent of walking speed, muscle activation differed between groups. In DPN group activation of ankle joint dorsal flexors was prolonged by 5–10% of the stride cycle.
Wuehr et al. (2014) [51]	36	>70	DPN (18) Control (18)	Walking speed Gait pattern Gait variability Temporal and spatial gait parameters	Gait analysis was performed using a 6.7 m long pressure sensitive carpet. Walking patterns were recorded during three different locomotion speeds (i.e., slow (SWS), preferred (PWS), and maximal walking speed (MWS)) with EO and during preferred walking with EC.	Alterations in the mean locomotion pattern of DPN group were mainly related to reduced walking speed. However, prolonged double support times, widened base widths, and increased gait variability during slow walking or with eyes closed appeared to be directly linked to peripheral sensory loss in patients.
Zurales et al. (2016) [52]	12	50–85	DPN (12)	Gait parameters on smooth and uneven surfaces	Optoelectronic kinematic techniques through two optoelectronic markers (infrared-emitted diodes) positioned 5 cm apart on an aluminum strip (10 cm 1.5 cm) that was bent at a 90-degree angle and inserted under the laces of each shoe at the midline.	An uneven surface is the strongest predictor of falls and injuries in older subjects with a spectrum of peripheral neurologic function.

SE: standard environment, CE: challenging environment, A/P: anterior/posterior, M/L: medial/lateral, EO: eyes open, EC: eyes closed, and BOS: base of support.