# An IoT-Based Non-Invasive Glucose Level Monitoring System Using Raspberry Pi
## 1 Introduction  
The Internet of Things (IoT) is a paradigm in which different devices used on a day-to-day basis have the ability to communicate with other devices, whether or not they are of the same type, with the aim of providing services through the internet. These devices can be household objects (lamps or appliances), street objects, or embedded devices especially created for particular applications; they are all called \"things\". Things not only acquire information from the environment and interact with the physical world, but also they can be equipped with identification, measurement, and process capabilities to provide context-aware services for achieving specific goals for information analytics, communications and final applications [1; 2; 3]. Since its inception, the IoT has been globally growing exponentially, bringing a broad spectrum of possible applications, from education [4; 5], the energy industry [6; 7], business decision making [8; 9], smart cities [10; 11; 12], air quality monitoring [13; 14; 15], among others. Despite the fact that the IoT has been extensively applied to almost every area in everyday life, it has also brought the opportunity to tackle problems in priority domains. Regarding this, the development and modernisation of health services constitute a major challenge for healthcareoptimisation. In a broader context, IoT technologies can be used for obtaining a solid infrastructure for recording, transmitting and processing large volumes of heterogeneous medical data generated from different types of sources, sensors and medical devices thus strengthening health services: e-health, telemedicine, people care and patient monitoring, which can be used at home, in hospitals or at external centres. The enhanced quality, and thus the acceptance, of e-health services have evolved jointly with hospital modernisation [16; 17; 18; 19]. One of the current applications of e-health in developed countries deals with the monitoring for both sick and healthy people in a range of disciplines: sports medicine, elderly health, chronic diseases monitoring, or disabled patients. This situation differs significantly in developing countries, in which the death rates are very high due to lack of monitoring and timely medical attention and treatments, where the majority of these deaths are preventable through quality care improvement. Due to the medical field is one of the areas with more potential for the use of IoT, there is an increasing interest in healthcare applications. Pervasive e-health applications use body sensor networks that may generate or record a vast amount of data that needs to be managed and stored for processing and future usage. To this end, there are many different electronic devices based on system-on-chip that permit the monitoring of a patient or a group of patients by sensing their biosignals information for being aware of their well-being [20; 21; 22]. According to the World Health Organization (WHO), the epidemic of diabetes mellitus (DM) in Mexico is catalogued as a national emergency. DM is a chronic non-communicable disease in which the body is unable to regulate blood glucose levels. There are two main types of diabetes: diabetes type-1 occurs when the pancreas is incapable to produce insulin, or produces only a scarce amount; insulin is essential to regulate the glucose concentration in blood and to convert glucose into energy. Diabetes type-2 takes place when the body cannot effectively use the insulin, and it is proliferating worldwide more rapidly than type-1 [23; 24]. Standard methods for measuring the blood glucose concentration are invasive, since they require either to collect a blood sample for a laboratory test, or to pick the fingertip for a capillary test. A capillary test is often used for monitoring due to its ease of use. However, patients require pricing their finger in different moments of the day, yielding discomfort and distress, thus hindering a proper glycaemia control. Facing this problem, minimally invasive glucometers have been developed.