Web-Based Cognitive Behavior Therapy for Depression in People With Diabetes Mellitus: A Randomized Controlled Trial

Background: Depression is twice as common in diabetes mellitus (DM) as the general population and is associated with adverse health outcomes, but access to evidence-based therapies such as cognitive behavioral therapy (CBT) is limited in routine diabetes care. Past research has shown that generic Internet-based cognitive behavioral therapy (iCBT) is an effective treatment for depression in the general population, but it has never been evaluated in people with comorbid depression and DM. Objective: The aim of our study was to examine the efficacy of a generic 6-lesson iCBT delivered over 10 weeks in people with major depressive disorder (MDD) and DM. Methods: Participants with comorbid MDD and DM (type 1 or 2) were recruited online and randomized to an iCBT program with therapist support provided by phone and email (n=42) or a treatment as usual (TAU, n=49) control group. Outcomes were assessed through Web-based self-report questionnaires and the trial was Web-based with no face-to-face components. Primary outcomes were self-reported depression (patient health questionnaire-9, PHQ-9), diabetes-related distress (problem areas in diabetes, PAID), and self-reported glycemic control (hemoglobin A1c, HbA1c). Secondary outcomes were general distress (Kessler 10-item psychological distress scale, K-10) and disability (short form 12-item, SF-12), generalized anxiety (generalized anxiety disorder 7-item, GAD-7), and somatization (PHQ-15). The iCBT group was assessed at 3 months. Results: A total of 27 participants (66%; 27/41) completed the iCBT program. Analyses indicated between-group superiority of iCBT over TAU at posttreatment on PHQ-9 (g=0.78), PAID (g=0.80), K-10 (g=1.06), GAD-7 (g=0.72), and SF-12 mental well-being scores (g=0.66), but no significant differences in self-reported HbA1c levels (g=0.14), SF-12 physical well-being, or PHQ-15 scores (g=0.03-0.21). Gains were maintained at 3-month follow-up in the iCBT group, and the 87% (27/31) of iCBT participants who were interviewed no longer met criteria for MDD. Clinically significant change following iCBT on PHQ-9 scores was 51% (21/41) versus 18% (9/49) in TAU. Conclusions: iCBT for depression is an efficacious, accessible treatment option for people with diabetes. Future studies should explore whether tailoring of iCBT programs improves acceptability and adherence, and evaluate the long-term outcomes following iCBT.