Relationship between diabetic peripheral neuropathy and foot type or plantar pressure

Abstract

Objective To investigate the relation of plantar pressure or foot type with diabetic peripheral neuropathy. Methods A total of 540 diabetic inpatients and outpatients (DM group, male 227, female 313, average age (59±12) years old, body mass index (BMI) (24±4) kg/m2) from Endocrinology Department of West China Hospital were enrolled with cluster sampling and examined by using Michigan Neuropathy Screening Instrument (MNSI). Matched healthy subjects (control group, male 84, female 147, average age (64±11) years old, BMI (23±4) kg/m2) were also enrolled in this study. All of the subjects were measured for foot type and relative peak plantar pressure in static state by plantar image scanner and plantar pressure measurement instrument. Chi-square test or t test was used for data analysis. Result There was no difference in mean relative peak plantar pressure (36±21 vs 36±22, t=-0.544, P=0.587) and relative peak plantar pressure of every site in static state between the two groups (P>0.05). Body weight and BMI were matched among three diabetic groups (the MNSI scores of group A were below 4; the MNSI scores of group B were between 4.5 and 6.5; the MNSI scores of group C were above 7) and the normal group. Compared to the control group, there was no difference in the relative average peak plantar pressure and relative peak plantar pressure of every site in static state (P>0.05). In the diabetic group, the incidence of hammer toes was twice as it in the control group (8.7% (47/540) vs 4.3%(10/231)). The mean MNSI scores of the diabetics with hammer toes (6.2±2.0 vs 5.4±1.2, t=2.145, P=0.032) and the diabetics with platypodia (6.6±2.1 vs 5.4±1.2, t=2.339, P=0.02) were higher, when compared to all of the diabetics. Conclusions MNSI shows little value in predicting plantar pressure; diabetics with hammer toes and platypodia may have higher MNSI scores.Patients who suffer from diabetic peripheral neuropathy and foot deformity or high plantar pressure are at higher risk of developing diabetic foot. Key words: Diabetes mellitus; Peripheral nervous system; Plantar pressure; Foot type