PROJECT SUMMARY Among adults with type 2 diabetes (T2D), daily diabetes self-management occurs in social contexts with close family and friends (herein, “family”). We recently developed, replicated, and longitudinally validated a typology of diabetes-specific family functioning. We identified four conceptually distinct profiles ("types") which were independently associated with diabetes self-management and psychological well-being, cross-sectionally and over time. The typology is applicable across diverse family structures, replicated in racially diverse samples, can be assessed through a survey tool, and has the potential to lead to breakthroughs in interventions for adults with diabetes. Therefore, within our recently completed randomized controlled trial (RCT) evaluating a family- focused mobile phone-delivered intervention we applied the typology post-hoc to explore intervention engagement and effects by family functioning type. From these analyses, we know which types did and did not benefit from the family-focused intervention and have developed hypotheses informed by mixed-methods preliminary data about how to tailor the existing intervention to benefit other types. Therefore, we propose to apply the family functioning typology proactively to inform an innovative, adaptive intervention to meet participants' evolving needs. The proposed type-informed adaptive intervention leverages our existing infrastructure to provide mobile phone-delivered intervention components, including: goal setting and monitoring (via phone coaching and text message support), skill building (via phone coaching), and the option to invite a friend or family member to participate in the intervention as a support person. These components will be turned on/off or adapted per most recent type assessment, tailoring both intervention form (individual vs. family) and content focus (disease vs. personal skills). We will enroll N=405 adults with T2D receiving primary care in the mid-South in a RCT lasting 16 months, including a 12-month intervention period, with assessments every 4 months. We aim to (1) evaluate the innovative type-informed adaptive mobile phone- delivered intervention relative to enhanced treatment as usual on hemoglobin A1c, diabetes distress, global well-being, diabetes self-efficacy and self-care behaviors, and (2) evaluate intervention effects for each type to discern which types experienced clinical benefit and inform which types need different intervention components. We will evaluate effects during the intervention, post-intervention, and sustained 4 months after the intervention ends. This project aligns with the NIH-wide strategic plan 2021-2025 to advance research on “giving the right treatment to the right patient at the right time” (p.12) and advances this plan through its novel focus on (a) a behavioral intervention and (b) family context as a key tailoring variable. Moreover, the proposed intervention is consistent with the American Diabetes As...