Changes in Person-reported Outcomes and Behavior Using the Accu-Chek SmartGuide CGM and Predict App

Continuous glucose monitoring (CGM) is widely used by people with insulin- treated diabetes to monitor glucose levels and support daily diabetes management. The Accu-Chek SmartGuide CGM system provides continuous glucose measurements and includes predictive features that are intended to provide information about possible future glucose trends. This study will investigate the use of the Accu-Chek SmartGuide with and without these predictive features in adults with type 1 diabetes or type 2 diabetes treated with intensified insulin therapy. The study will be conducted remotely in Germany through the dia\*link online panel. No in-person study visits are planned. Participants will use the Accu-Chek SmartGuide CGM system for a total of 6 weeks. The study consists of two consecutive phases. During the first 2 weeks, participants will use the Accu-Chek SmartGuide CGM without the Predict App and therefore without the predictive features. This phase provides a period in which CGM data and self-reported outcomes can be assessed before the predictive features are introduced. After 2 weeks, participants will receive training on the Predict App and begin a 4-week period using the Accu-Chek SmartGuide together with the Predict App. Participants will complete online questionnaires at the end of the first 2 weeks and at the end of the 6-week study period. The questionnaires assess fear of hypoglycemia, sleep quality, confidence in preventing hypoglycemia, diabetes- related distress, and diabetes empowerment. During the first 2 weeks and the last 2 weeks of the study, participants will also complete short ecological momentary assessment (EMA) questionnaires twice daily using a smartphone app. The morning assessment asks about sleep quality and confidence in preventing hypoglycemia. The evening assessment asks about the use and evaluation of CGM functions, including trend arrows, alarms, and predictive features. Participants will also be asked about possible therapy adjustments, satisfaction with the CGM functions, and diabetes- related distress, including distress related to hypoglycemia, hyperglycemia, and glucose variability. CGM data will be collected throughout both study phases. These data will include measures such as time in glucose ranges, hypoglycemia, hyperglycemia, glucose variability, and mean glucose levels. The study will assess changes in these measures between the two study phases. The primary outcome is the change in fear of hypoglycemia during the 4-week period in which participants use the Accu-Chek SmartGuide together with the Predict App. Secondary outcomes include changes in other psychosocial outcomes, diabetes-related behaviors, use and evaluation of CGM alarms and trend arrows, and CGM-derived glucose measures. In addition, a subgroup of 10 participants will be invited to take part in a semi-structured online interview after completing the study. The interviews will explore participants' experiences with the predictive features, their confidence and trust in these features, perceived benefits in everyday diabetes management, and suggestions for improvement. Participants will be selected to achieve a balanced representation with regard to age, sex, and type of diabetes.