Objective <p>This study investigates the interplay between family support, health literacy, and self-management behaviors in newly diagnosed patients with type 2 diabetes mellitus (T2DM).</p> Methods <p>A cohort of 354 newly diagnosed patients with T2DM participated in this longitudinal study. Health literacy, self-management behavior, and family support were assessed using the Health Literacy Scale, Diabetes Self-Management Behavior Scale, and Family Support Scale at baseline, 3 months, and 6 months post-diagnosis.</p> Results <p>Health literacy and self-management abilities demonstrated significant correlations at both 0–3 months (β = 0.32; β = 0.23) and 3–6 months (β = 0.37; β = 0.28). Family support was a significant predictor of health literacy during the 0–3 month period (β = 0.23), with a reduced effect size at 3–6 months (β = 0.18).</p> Conclusions <p>Health literacy and self-management abilities in newly diagnosed patients with T2DM follow a co-evolutionary spiral model, with family support serving as a key driver in the initial phase. Clinical interventions should establish a dual-core “education-behavior” linkage system, focusing on enhancing family empowerment in the early stage (0–3 months) and transitioning to a cognitive improvement model driven by behavioral feedback in the later stages (3–6 months).</p>