Abstract
BACKGROUND: Type 2 diabetes mellitus (T2DM) presents significant comorbidity with emotional disorders, with approximately 25% of patients experiencing clinically significant depression and anxiety symptoms. While some disorder-specific interventions, such as cognitive-behavioral therapy, have demonstrated efficacy in addressing emotional symptoms in T2DM patients, they often do not fully address the interconnected nature between diabetes and emotional distress, highlighting the need for integrated, transdiagnostic treatment approaches. This study evaluated the efficacy of group-based transdiagnostic cognitive-behavioral therapy (gTCBT) for improving depression, anxiety, quality of life, and medication adherence in adults with T2DM and comorbid emotional disorders. METHODS: This randomized controlled trial recruited 52 participants with T2DM and emotional disorders. Participants were randomly assigned to either a 12-session gTCBT intervention based on the Unified Protocol (n = 26) or waitlist control (n = 26). Primary outcomes included Beck Depression Inventory-II and Beck Anxiety Inventory. Secondary outcomes were assessed using the Diabetes Quality of Life questionnaire for quality of life and the Morisky Medication Adherence Scale for medication adherence. Assessments were conducted at pre-treatment, post-treatment, and one-month follow-up. RESULTS: 48 participants completed the study (23 intervention, 25 waitlist). Mixed-model ANOVAs revealed significant time × group interactions for all outcomes (p < .001). The intervention group demonstrated large effect sizes for depression (g = 2.48), anxiety (g = 1.65), quality of life (g = 1.72), and medication adherence (g = 1.66) improvements from pre- to post-treatment. Effects were sustained at one-month follow-up. CONCLUSIONS: gTCBT effectively reduced emotional symptoms and improved diabetes-related outcomes in patients with T2DM and comorbid emotional disorders. The transdiagnostic approach offers a effective intervention for addressing complex comorbidities in diabetes care settings. TRIAL REGISTRATION: This randomized clinical trial comprised an intervention and a waitlist that was registered in the Iranian Registry of Clinical Trials (ID: IRCT20241116063741N1). (Registration Date: 05/07/2025).