Type 2 diabetes (T2D) can be prevented or delayed through a healthy lifestyle. Digital behavior change interventions (DBCIs) may offer cost-effective and scalable solution to support lifestyle improvement. This study investigated associations between user engagement with a habit formation based DBCI (the BitHabit app) and changes in T2D risk factors over a 12-month period in 963 participants at risk of T2D. User engagement was characterized by calculating use metrics from the BitHabit log data. User ratings were used as a subjective measure of engagement. The use metrics and user ratings were the strongest associated with improvements in diet quality. Weak positive associations were observed between the use metrics and changes in waist circumference and body mass index. No associations were found with changes in physical activity or plasma glucose levels (fast- ing and 2h oral glucose tolerance test). To conclude, increased use of the BitHabit app can have a positive impact on T2D risk factors, especially on diet quality.