Suboptimal self-care by individuals with diabetes mellitus (DM) is a significant public health concern. The common-sense model (CSM) proposes that illness representations are associated with coping and health outcomes across various conditions. The present study examined the efficacy of a CSM-based intervention in improving illness representations, self-care, self-care self-efficacy, use of adaptive coping strategies, and glycated hemoglobin among individuals with type 2 DM (T2DM).

A two-arm randomized controlled trial was used. A total of 455 T2DM patients were recruited from an outpatient DM clinic and randomized to an intervention group that consisted of five weekly group-based education sessions or a control group that received five weekly educational booklets. Evaluation was conducted at baseline and at 1- and 6-month follow-up.

The 2 × 3 linear mixed-model analysis using a modified intention to treat revealed a significant time by condition interaction effect on level of self-care (F(2,840) = 7.78, p < .001), self-care self-efficacy (F(1.89,794.57) = 14.40, p < .001), and use of adaptive coping strategies (F(1.94,812.93) = 4.75, p = .010) in which participants in the intervention group reported greater improvement in such aspects compared with those in the control group. A significant time effect was observed in some dimensions of illness representations. No significant effect was found in glycated hemoglobin. Participants reported positive feedback to the intervention and perceived improvement in various domains.

The CSM-based intervention was effective in improving self-care and coping among DM patients. The intervention also demonstrated high feasibility and acceptability. Findings provided important insights in improving health-related outcomes for patients with T2DM using the CSM framework.