Change Of Plantar Pressure In The Patients With Type2Diabetes Mellitus And Some Influencing Factors

Objective： In2011, there were366million people with diabetesworldwide, and it has been estimated that the number may surpass552millionby2030. Diabetic foot, as one of the most serious diabetic complications,impairs quality of life, increases mortality and results in high economic burdenfor the family and the society.15%of the patients with diabetes would haveulcer or gangrene in the life. As investigated, lower limb amputations in thepatients with diabetes accounted for more than50%of all amputations andtwo-thirds of those arised as a result of ulceration of the foot. High plantarpressure is a key factor to predict ulceration in foot of patients with diabetes,with the correlation of70%~90%, but there is no optimal cut-point for clearlyscreening patients for the risk of foot ulceration. High plantar pressure of thosewith diabetes correlates with a number of factors, especially limitation of jointmobility and neurological dysfunction. There are other associated factors, suchas body weight, body mass index (BMI), foot deformity, callus of the footplateand so on. But it is not clear which one plays a more significant role in theincrease of the plantar pressure of patients with diabetes. If such variablescould be identified, interventions can be taken specifically to prevent patientswith diabetes from high plantar pressure and ulceration in an economic-friendfashion. Plantar pressure of those with diabetes has been studied in the westernduring the past20years. However, there is little information about the planterpressure of the Chinese patients with type2diabetes mellitus and theinfluencing factors, and further study is required. The purpose of the study wasto identify the correlations between high plantar pressure in the patients withtype2diabetes mellitus and some clinical characteristics obtained easily andto find the influencing factors.Methods:100patients, recruited from the Department of Endocrinology, Third Hospital of Hebei Medical University, from February,2012to August,2012, were included in this study. Age, gender, height, weight, duration ofdisease, shoe size and the height of heels was recorded. The examination ofthe foot included the nutrition of skin and callus. Others recorded weresweating, the history of infection, ulcer, blister and unnormal feeling. Thefootscan gait system was applied to detect the dynamic plantar pressure. Fivetrials were collected from each patient and three ideal one with wholefootprint were selected for the following analysis. The footscan gait systemgave important information, the max pressure, the max force and the maximpulse, as the patients walking on the platform. The data were obtained from10parts of foot on the basis of anatomical locations. Mean values of allparameters for each part of the left and right feet were calculated. Only plantarpressure data of the left foot were used for the following data analysis. TheSemmes Weinstein monofilament test kit (10g) was employed to know thesensation of foot. To calculate the ankle-brachial index (ABI), the systolicblood pressure of the ankle artery in each was divided by the systolic bloodpressure of the brachial artery. Diagnostic Ultrasound System was used todetect the blood vessels of the lower limbs, including lumen, inwall,intima-media membrane and plaques. Glycated hemoglobin (HbA1c), theconcentration of fasting blood glucose (FBG), fasting serum insulin (F-INS),cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol(HDL-C), low-density lipoprotein cholesterol (LDL-C), very low-densitylipoprotein-cholesterol (VLDL-C), apolipoprotein A Ⅰ (ApoA Ⅰ),apolipoprotein B (ApoB), lipoprotein(a)[lp(a)] and urinealbumin-to-creatinine ratio (UACR) was tested. The pathological changes offundus oculis were examined and identified by the ophthalmologists. After6months,35patients were followed. Weight and the history of ulcer wererecorded and all the patients were examed for plantar pressure, the sensationof foot and ABI.After testing for normality, all normally distributed continuous data in thefirst examination were expressed as means±standard deviations, and other continuous data were expressed as median with interquartile range. Spearmancorrelating was used between the plantar pressure variables and some clinicalcharacteristics variables (the continuous data and rank data). Nonparametrictests for independent samples were used to evaluate any potential differencesamong the plantar pressure data separated by categorical variables. Multiplelinear regression analysis was used in the variables demonstrated to bestatistically significantly correlated with plantar pressure variables. Abackwards selection algorithm was selected. When the data of weight, ABIand plantar pressure from two examinations was compared, paired-samples ttest was used for a double variable normal distribution, and nonparametric testwas used for others. Bivariate correlating was used between the variation ofplantar pressure and the variation of weight/ABI in6months, pearsoncorrelating for a double variable normal distribution and spearman correlatingfor others.Results: By the single factor analysis, positive and significantcorrelations were identified between all the plantar measurements under eachregion except of toes and weight. In addition, the max pressure under the firstmetatarsal head showed no correlation with weight, either. Significantcorrelations were seen between the majority of plantar pressure measurementsand other four variables (height, shoe size, ApoAⅠ and ABI). The max forceunder the second metatarsal head and lateral part of heel might get lower withage (rs=-0.211, P=0.035; rs=-0.239, P=0.016). A negative correlation wasgot between the impulse under the third metatarsal head and the height of shoeheels (rs=-0.203, P=0.043). A negative correlation was observed betweenthe max pressure under the first toe and the sensation of foot (rs=-0.197, P=0.050). A positive correlation was seen between the impulse under the firstmetatarsal head and FBG (rs=0.218, P=0.029). The max force and theimpulse under the third metatarsal head as well as the max force medial part ofheel had correlation with LDL-C (rs=-0.224, P=0.025; rs=-0.204, P=0.041; rs=-0.208, P=0.038). No correlation was observed between plantarpressure measurements and other variables. In the categorical variables, some plantar pressure data had association with gender and the history of ulcer.The backwards regression modeling indicated that3.5%～9.6%of thevariability in ten measurements under six regions could be explained byweight alone. The max force under the first toe was influenced by ApoAⅠ (β=-0.267, P=0.007) and the max pressure under the first toe was influencedby the sensation of foot (β=-0.261, P=0.009). The history of ulcer in footmight be a factor influencing the pressure measure under the second to thefifth toes (β=-0.213, P=0.033). The higher the height (β=0.220, P=0.028)or the fasting blood glucose (β=0.168, P=0.092), the higher the impulseunder the first metatarsal head.14.8%of the variability in the max force of thesecond metatarsal head and14.1%of the variability in the impulse of thesecond metatarsal head both could be explained by height, ABI and ApoAⅠ,and6.7%of the variability in the max pressure of the second metatarsal headcould be explained by ABI and ApoAⅠ. The max pressure under the thirdmetatarsal head was only influenced by ApoAⅠ (β=-0.196, P=0.051).Furthermore, it seemed that males may have higher impulse under the lateralpart of heel than females (β=-0.250, P=0.012). As R2values ranged from0.035to0.148, it should be underlined that the multiple regression modelscould explain only the minority of the variability in the plantar pressuremeasurements.In6months, all of the plantar pressure increased, except for the maxforce, the max pressure, the impulse under the second to the fifth toes and theimpulse under the first toe. No difference was found in the history of ulcer andthe sensation of foot. Weight and ABI didn’t change significantly in6months.The increasing of plantar pressure in that period had no correlation with thechange of weight, the history of ulcer, the sensation of foot and ABI.Conclusion:1Plantar pressure had correlation with12factors (age, gender, height,weight, shoe size, the height of heels, the history of ulcer, the sensation of foot,ABI, FBG, LDL-C and ApoAⅠ).28factors (gender, height, weight, the history of ulcer, the sensation of foot, ABI, FBG and ApoAⅠ) were the influencing factors of plantar pressure.3In6months, the most of the plantar pressure got higher. But the changehad no correlation with the change of weight, the history of ulcer, thesensation of foot and ABI.