The rising rates of type 2 diabetes mellitus (T2DM) pose a major health challenge, especially for adults at high risk of developing the disease. Without early intervention, a substantial proportion of these individuals will eventually develop the disease, diminishing their quality of life, leading to limitations in daily activities and elevated psychological distress. Mobile health (mHealth) interventions such as the MyDiPP application have been proposed as a potential tool to support diabetes prevention; however, evidence on their effects on HRQoL in high-risk populations remains limited. This study aimed to evaluate the effect of the MyDiPP mobile application intervention on the HRQoL among adults at high risk of developing T2DM. This randomised controlled trial (RCT) involved 112 high-risk adults from Kuala Terengganu, Terengganu, Malaysia. They were randomly assigned to either the MyDiPP mobile application intervention group (n=56) or a control group (n=56) receiving standard health education. Changes in HRQoL at 6 and 12 months were analysed using repeated measures ANCOVA with an intention-to-treat (ITT) approach. Findings showed limited improvements across HRQoL domains following the MyDiPP intervention, particularly in role emotional (RE) and the mental component summary (MCS), reflecting a mild but encouraging influence on HRQoL. Therefore, further research is required to determine whether largerscale studies can yield more substantial outcomes.