## 2 State of the Art
### Mobile Applications for Diabetes Management  
The universe of mobile applications for diabetes care is enormous. A first step consists in determining the utility of apps. One standard classification includes exercise and fitness apps, med adherence, weight management, blood glucose trackers, support, healthcare professional apps, and educational simulators. There is extensive availability of applications related to any of the previously mentioned apps, but few efforts are related to educational simulators for smartphones. One interesting branch of smartphone applications for health care is the simulators. In this paper, we are specifically interested in creating a smartphone-based simulator of glucose-insulin metabolism. In recent years, there have been advances in creating models that can replicate the behavior of parts (or entire) of human organisms and their corresponding implementation as a computer simulation. A smartphone-based simulation can be useful for patients with recently diagnosed diabetes to help them estimate the insulin doses and food intake, but also for patients at risk of developing diabetes or without diabetes, for contributing to raising awareness of the benefits of changing their food consumption and exercise habits. In [25], a review of several diabetes simulators is presented, but the applications reported in that paper is out of the scope of this work, since there is an interest in providing a realistic simulation of blood glucose levels. There are several reviews of applications for diabetes management. In [26], a set of critical factors to be considered when designing diabetes management applications are explored. These factors come from patient demographics, technology costs, platform varieties, and ease of use. They also categorize the applications in the following classes: blood glucose logging, nutrition databases, carbohydrate tracking, tracking physical activity and weight, data-sharing and social support, and short messages and reminders. An important point to consider is that the FDA does not approve most applications. In [27], several commercial applications for diabetes management available on the Apple App Store and articles published in relevant databases are reviewed. The reviewed applications support self-management tasks such as physical exercise, insulin dosage or medication, blood glucose testing, and diet. Other support tasks considered include decision support, notification/alert, tagging of input data, and social media integration. Analysis indicates that application usage is associated with improved attitudes favorable to diabetes self-management. Limitations of the applications include lack of personalized feedback; usability issues, particularly the ease of data entry; and integration with patients and electronic health records. In much more detail, in [28], it is concluded that a critical feature strongly recommended by clinical guidelines--namely, personalized education is not assimilated in current diabetes applications. In [29] a critical assessment was reported of several smartphone apps for calculating insulin dose. The conclusion was that popular apps offering insulin dose calculations carry a risk of incorrect dose recommendations ranging from those that might lead to suboptimal disease control to those with potentially life-threatening consequences. In [30], an analysis of the benefits of smartphone apps for type 2 diabetes mellitus (T2 DM) self-management was presented. It can be concluded that more research with valid study designs and longer follow-up is needed to evaluate the impact of health apps for diabetes care and self-management, specifically for T2 DM. In [31], both Heuristic and keystroke level modeling (KLM) are used to measure efficiency for each analyzed mobile diabetes management application for patients with Type-1 Diabetes Mellitus. With recent advances in connectivity technologies, there are some efforts to build tools based on cloud computing [32] or social network support [33; 34].