###### Abstract
Electrical impedance spectroscopy system. The application of electrical impedance has been favorable due to its safety, low cost, efficacy and applicability, as in the case of cancer diagnosis and characterization of biomaterials. Nowadays, it is being applied to the diabetic foot. Such is the case of [PERSON] et al. who performed electrical impedance measurements in a range of 0 to 50 kHz in six patients with diabetic foot ulcers and a control group of eight healthy subjects. Differences were found between ulcerated and non-ulcerated legs, in which the electrical impedance values were much lower in the healthy feet [8]. [PERSON] et al. developed an electrical impedance analyzer for the analysis of diabetes. Their results showed that people with diabetes have a curve relating their bioimpedance over a frequency range from 10 kHz to 80 kHz [9]. Skin macule characterization system. Diabetes mellitus is associated with different dermatologic conditions. Dermatologic manifestations can be the first indicator of diabetes in some patients, and certain conditions may indicate poor control of the diabetic patient [10]. Infrared emission thermography system (IRT). Currently, studies with IRT have reported efficiency in preventing diabetic foot ulcers, conducting a thermal evaluation of the plantar surface of the foot. [PERSON] et al. used infrared thermography to develop and evaluate a portable sock to monitor foot temperature in diabetic subjects. It was observed that there is a relationship between the areas with greater temperature changes and the risk of ulceration in diabetic patients [4]. [PERSON] et al. involves the validation of a smartphone-based IR camera against a high-end IR camera for diabetic foot assessment. Contralateral temperature differences of the entire plantar foot and nine pre-specified regions were compared for validation. Near-perfect agreement was found for temperature measurements on both the sole of the foot and the combined prespecified regions, with diagnostic accuracy of 94% and 93% sensitivity, and 86% and 91% specificity [11]. Virtual platform for the diabetic foot ulcer. Currently, there are different electronic advances to help diabetic patients and medical professionals to monitor the state of their feet for the prevention and follow-up of ulcers, such is the case of [PERSON] et al. They work with a mobile application for the detection of ulcers and analyze the thermal distributions, looking for a temperature difference greater than 2.2 \({}^{\circ}\)C and identifying the regions with possible ulcers [12]. To promote foot care in diabetic people, [PERSON] et al. present their virtual platform PEDCARE; its content and appearance were validated, registering a 0.95 content validity index [13]. [PERSON] et al. are working with a mobile application that seeks to help nurses to choose an appropriate topical treatment for diabetic foot ulcers [14]. In this article, we present different systems that claim to be future supports in the diagnosis of diabetic foot using tissue analysis with non-invasive methods. Today the diagnosis of this disease is made when it has advanced enough to show ulcers or advanced tissue damage. Currently, there are no systems that are used for the early detection of diabetic foot, which means that these systems will have a great impact in the future since, at this time, they are easy to use for doctors and patients; that is, they are user-friendly in terms of their understanding of results, in addition to being easy to access, easy to install and low cost.