## 6 Conclusions  
The results of eye-tracking studies showed how the target users of the T1 DCoach application, divided into three groups, dealt with using the T1 DCoach application: Patients (G1), Caregivers (G2) and Educators (G3). Even though, in order to increase the effectiveness of learning how to use the application, dedicated instructions were prepared for each user group that show the application's capabilities, people participating in usability tests obtained different results. It turned out that the best achievements were achieved by Educators, who performed the tasks included in the research scenarios the fastest, with the least cognitive effort and with the fewest errors. In turn, Patients (G1) achieved the poorest results and therefore had the greatest problems with implementing the scenarios. It can therefore be assumed that the good results for Educators were related to their extensive knowledge and experience of diabetes and high digital competences. The poorer results for young Patients (G1) in using the application were most likely caused by lower skills in coping with the disease. It is worth noting that computer skills facilitating the use of the application also varied depending on age. They were higher in the older group of patients.  
The basic conclusion from the SUS examination of the interface quality of the T1 DCoach mobile application is that the T1 DCoach application interface exceeds the quality of the industrial standard by over 8%. The high quality of the interface was therefore confirmed in the study. Similar conclusions can be drawn from focus group interviews.  
In addition to cosmetic changes to the interface, the research put forward the following recommendations:  
* implement a male avatar (done in the form of MIKI--Figure 7);
* do not limit the values entered into the application during validation (towards positive values) (applies to bolus, food, etc.)--this is to teach responsibility in everyday life (that requirement was not provided by the application developers);
* highlight the existence of a side menu;
* improve the visibility of meals in the Food History;
* lower the sensitivity of the sliders and add windows for entering values;
* change the order of displaying historical data so that the newest are at the top of the list.  
The recommendations were introduced into the application, which improved the quality of its interface. This was confirmed in subsequent acceptance tests of the application in real conditions.  
Conceptualization, M.M.; methodology, M.M., M.P.-W. and M.D.; software, M.D.; validation, M.M., M.P.-W. and M.D.; formal analysis, M.M.; investigation, M.M., M.P.-W. and M.D.; resources, M.M.; data curation, M.D.; writing--original draft preparation, M.M., M.P.-W. and M.D.; writing--review and editing, M.M., M.P.-W. and M.D.; visualization, M.D. and M.M.; supervision, M.M.; project administration, M.M.; funding acquisition, M.M. All authors have read and agreed to the published version of the manuscript.  
This research was funded by Polish National Center for Research and Development under the _Things are for people_ program (Grant No. Raceczy sa dla ludzi/0062/2020-00).  
The research procedure and documentation received a positive opinion from the Scientific Research Ethics Committee of the Lublin University of Technology No. 1/2022 of 13 April 2022.  
Informed Consent Statement: Informed consent was obtained from all subjects involved in the study.  
The original contributions presented in the study are included in the article; further inquiries can be directed to the corresponding author.  
The authors declare no conflicts of interest.