BACKGROUND: Studies have shown the existence of health concordance between patients with type 2 diabetes mellitus (T2DM) and their spouses, and also that spouses could influence the effect of self-management, benefiting patients' health. However, these studies are heterogeneous and the evidence is inconclusive. OBJECTIVE: To synthesize evidence from published randomized controlled trials: the interventional effects and the quality of study performance, also to identify the research gap and the directions for future studies. METHODS: We performed the scoping review by following the PRISMA-ScR guidance. We searched and examined the reports from MEDLINE, EMBASE, PsychInfo, CINAHL Plus by the pre-specified criteria. Key characteristics and information of eligible reports were extracted, analysed and synthesized comprehensively, and the results were presented in the form of words and diagrams. RESULTS: We identified 5 reports from 4 studies out of 3479 records included. Qualified studies indicated a positive effect of couple-based interventions on couples' distress. Insufficient evidence on physiological health or health behaviours was identified owing to the small number of included studies and inconsistent assessment outcomes. The methodological quality across these studies was generally low due to inadequate reporting of study process and substantial biases. CONCLUSIONS: Couple-based interventions for patients with T2DM showed small effects on the couple's distress while the effects of other outcomes were inconclusive. Future studies should strengthen methodologies by using standard measures of core diabetic outcomes, including detailed assessments of implementation process, and taking a dyadic approach to systematically examine the effects.