1. Introduction

The risk of diabetes foot (DF) in diabetes patients’ lifetime is 19% ~ 34%, and the risk of recurrence in 1-5 years after cure is as high as 40% ~ 65%, which has caused huge economic burden to families and society [1]. Especially in the elderly population, according to statistics, the prevalence of diabetes in the elderly population in China is 30.2% [2]. Diabetic foot has gradually become one of the most serious chronic complications affecting the quality of life of elderly diabetic patients. The guideline emphasizes the idea that prevention is more important than treatment for diabetic foot, and points out that prevention of DF is the key to reducing its incidence, amputation rate and mortality [3]. High-risk foot, as the early stage of DF, are defined as the presence of peripheral neuropathy and/or peripheral vascular disease and/or foot deformity, or a history of foot ulcers/amputations, but no active foot ulcers at present [4]. Some studies have pointed out that high risk foot patients can be screened through foot examination, and effective preventive measures can be taken to prevent 50% of patients from diabetes foot or amputation [5]. At present, about 90% of the elderly in China mainly provide for the aged at home, and most of the elderly do not pay enough attention to diabetes foot [6]. The key to prevent diabetes foot is whether diabetes patients have been properly assessed and intervened in the community [7]. Therefore, this study took elderly type 2 diabetes patients in the community as the research object, identified high-risk foot groups through foot examination, and analyzed its related factors, so as to provide reference for the prevention and management of chronic disease complications in the community.

2. Materials and methods

3. Result

3.2. Results of single factor analysis of influencing factors of high risk foot of elderly diabetes mellitus

By comparing the general data and disease related data of the elderly diabetes high-risk foot group and the elderly diabetes low-risk foot group, it is found by t-test or chi square test that there are statistically significant differences between the two groups in terms of age, diabetes course, glycosylated hemoglobin (HbA1c), blood glucose treatment methods (insulin injection group and non insulin injection group), diabetes retinopathy, hyperlipidemia, cerebrovascular surgery history, cardiovascular surgery history, etc. (P < 0.05), see Table 1 for details.

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Table 1. Univariate analysis of risk factors for high-risk foot in an elderly community (n = 269).

https://doi.org/10.1371/journal.pone.0313794.t001

3.3. The results of binary logistic regression analysis on the influencing factors of high-risk foot of elderly diabetes

Taking whether there is a high-risk foot as the dependent variables and the statistically significant variables in the univariate analysis as the independent variable, binary logistic regression analysis was carried out. The results showed that age (OR = 1.083,95% CI: 1.040 ~ 1.127), HbA1c (OR = 1.269,95% CI: 1.003 ~ 1.604), diabetic retinopathy (OR = 2.240,95% CI: 1.080 ~ 4.646), hyperlipidemia (OR = 2.304,95% CI: 1.248 ~ 4.255), and the way of blood glucose treatment (OR = 2.597, 95% CI: 1.400 ~ 4.815) were independent of the high-risk foot of elderly diabetes (P < 0.05), see Table 2 for details. The Hosmmer Lemeshow fitting test results show that the chi square value is 11.158, with a P-value of 0.193, which is greater than 0.05.

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Table 2. Logistic regression analysis of risk factors for high-risk foot in an elderly community.

https://doi.org/10.1371/journal.pone.0313794.t002

4. Discussion

As one of the serious chronic complications of diabetes, diabetic foot is characterized by high incidence, high disability rate and high fatality rate [3], and its mortality rate is much higher than that of most cancers [10]. Following the concept that prevention is more important than treatment, the screening of high-risk foot for diabetic patients and targeted intervention for high-risk foot patients can effectively reduce the occurrence of diabetic foot [11]. According to the International diabetes Foot Working Group (IWGDF) high risk foot grading system, the detection rate of high risk feet (Grade 1, Grade 2 and Grade 3) in this study is 51.7%. Compared with the results of Sun Shujuan et al. [12] (42.97%) and Banik et al. [13] (44.5%), the detection rate of high risk feet in this study is higher than both, which may be related to the relatively high age of the elderly in the community as the object of this study. The P value of Hosmmer Lemeshow fitting test is 0.193, which is greater than 0.05. The null hypothesis is accepted, indicating a good fit between the observed data and the regression model. The results analyzed by the binary logistic regression model truly and reliably reflect the true relationship between the original variables. Logistic regression analysis of this study showed that age, high glycosylated hemoglobin, retinopathy with diabetes, hyperlipidemia, and blood glucose treatment (insulin injection group) were independent risk factors for high-risk foot of elderly diabetes.

Age is the risk factor of high-risk foot in elderly patients with diabetes, which is consistent with the research results of Kisozi et al. [14]. In this study, the average age of the elderly people with high-risk foot of diabetes is 72.57 ±  7.65 years old, which is larger than the average age of the people with low-risk foot (70.17 ±  6.27 years old). Logistic regression analysis found that for every 1-year-old increase in age, the risk of developing high-risk foot increased by 1.083 times. The reason may be that with the increase of age, the nerve conduction delay is longer, the amplitude is smaller, and the conduction speed is slower [15].

The increase of HbA1c indicates that the blood sugar level of patients is poorly controlled. Long-term high blood sugar will cause non-enzymatic glycosylation of amino acid components on the blood vessel wall, resulting in vascular smooth muscle hyperplasia, aggravating the occurrence of atherosclerosis, and increasing the risk of peripheral vascular diseases [16,17]. At the same time, this study found that the risk of developing high-risk foot in insulin users was 2.597 times that of non-insulin users. It is generally believed that insulin users have a longer course of diabetes, which may be related to the long-term hyperglycemia causing swelling, degeneration and even necrosis of nerve fibers, leading to nerve demyelination, and then peripheral neuropathy [18].

Diabetic retinopathy is an independent risk factor for high-risk foot, which is consistent with the conclusions of Al-Rubeaan et Al. [19]. The reason may be that the two have some common pathophysiological basis, that is, multiple mechanisms such as oxidative stress mediated by long-term hyperglycemia, glycosylation end products and chronic inflammatory response [20], which ultimately lead to peripheral nerve and vascular lesions.

Dyslipidemia is an independent risk factor for high risk foot. Data from this study showed that patients with hyperlipidemia had a 2.304 times higher risk of developing High-risk foot than those without. Consistent with the conclusions of many studies [21–23], on the one hand, it may be related to hyperlipidemia promoting the formation of atherosclerotic plaque; On the other hand, the reason may be related to the oxidative stress and endothelial dysfunction of dorsal root ganglion sensory neurons caused by abnormal blood lipids, which in turn leads to peripheral neuropathy [24].

Finally, it should be pointed out that due to the limitations of conditions, random sampling was not realized, but convenient sampling was chosen. Therefore, the generalizability of this study has some potential limitations.

5. Conclusion

Among the elderly in the community, the overall detection rate of high-risk foot of diabetes is high, and it is significantly related to the elderly, elevated glycosylated hemoglobin, hyperlipidemia, blood glucose treatment, and diabetes retinopathy. The research results show that community medical staff should regularly screen the feet of elderly diabetes patients in the community according to the recommendations of IWGDF, and take targeted measures according to the classification of High-risk foot to reduce the harm of diabetes feet to patients, families and society.

Supporting information

Acknowledgments

The authors would like to thank the staff of Xinjiekou Community Hospital for their strong support, and the participants who volunteered to participate in this study.