## 3 Challenges to be Overcome in an ICT--Based Diabetes Management System  
After a complete review of the scientific literature, it is possible to identify some characteristics to be improved in order to draft a holistic solution for management of DM1 by means of ICT technologies. Firstly, the potential of CGM as a masterpiece in diabetes control and management is still unfolding. Unfortunately, this device has not been developed enough until recent years. Even today, the CGM devices that are available on the market present some problems, such as lack of accuracy, decalibration, and sometimes a short usable period. Moreover, complaints are frequently made about the lag time between the data provided by the CGM and the real glucose level in the bloodstream of the patient. This is due to the fact that the CGM is not measuring directly from the blood; the value that the CGM device offers is an estimate based on the interstitial fluid glucose that exists under the skin, whose magnitude is delayed by some minutes with respect to the actual value that are present in the bloodstream. This fact can be perceived as a disadvantage. However, recent research has found that this lag time is not more than 5-10 min [37]. Moreover, mathematical methods can suitably compensate for the lack of accuracy due to this delay. In fact, some of the tests deployed by [PERSON] [38] confirm a delay of just six minutes. Luckily, novel technologies in this area make more reliable, affordable, and user-friendly devices possible. This will necessarily lead to an increasing number of studies that include CGM in innovative diabetes management analysis. In another vein, it is remarkable that previous works suffer from the absence of global monitoring of the patient. Moreover, apart from the obvious features that have an impact on diabetes control (glycemia itself, insulin, meals), studies have proven that other variables can influence glycemia trends significantly. For example, physical activity is widely assumed to be an influencing variable [39], and its monitoring is starting to be essential in diabetes management, usually being recorded with accelerometers. Heart-rate is also an emerging feature that is beginning to be considered as a required variable for a realistic diabetes management system. However, the potential of this component is often undervalued and is usually related only to hypoglycemia [40]. Other variables, such as exhaled breath [41] or polarimetry to monitor changes in the aqueous humor of the eye [42], have been studied,but such research is only at an early stage. On the other hand, other variables whose consideration makes intuitive sense are studied, at most, in a controlled environment under laboratory conditions of temperature, perspiration, and so on, and in isolation. Others, like the influence of schedule or weekday, are well-known [43], but have not been studied in the context discussed in this work. Therefore, to the best of the authors' knowledge, there is not a global study in which all of them are monitored at the same time. In addition, the way in which these features are treated lacks an expanded vision. Some variables, like insulin, could be treated in different ways, for instance, from an \"on board\" perspective, both basal insulin and remaining fast-insulin, which can act with low (but noticeable) intensity for several hours, are taken into account. Although this concept has been introduced for insulin, it could be extended similarly to other features. This possibility has not been studied yet. Going further, it has not been possible for the authors of this paper to find a work that compares and ranks the importance of all of the features that have an impact on diabetes control and offers a definitive set of variables that are to be taken into account. The potential of new improvements in ICT has still not been exploited to its full extent. To begin with, a uniform way to deal with information is needed, and in this sense, approaches like the mentioned HL7 have established a path to follow.