Background: Diabetes distress is a common emotional issue for those living with diabetes, which has the potential to negatively impact well‐being, management behaviors, and HbA1c levels. These implications have led to diabetes distress becoming an important consideration in diabetes healthcare and management. Nonetheless, discussions remain ongoing on how to best conceptualize this experience. Recent research has attempted to enhance conceptualization by considering the underlying emotional mechanisms that may underpin the highly contextualized experience of diabetes distress. Qualitative insights can further add to these understandings; however, the research in this remit is yet to be systematically reviewed. This review therefore sought to add to the growing body of literature attempting to better conceptualize diabetes distress and the underlying mechanisms that may contribute to this experience. A secondary aim was to leverage this understanding to consider ways to improve patient–healthcare interactions.Methods: A qualitative systematic review and thematic synthesis was undertaken. Eligible studies were identified through PsycINFO, MEDLINE, CINAHL, and EMBASE databases from November 2020 to May 2021. Study quality was assessed using the McMaster Critical Review Form.Results: Nineteen papers were included in the review. The analysis resulted in seven descriptive themes which contributed to three analytical themes: (1) threatened autonomy, (2) sense of helplessness, and (3) negative sense of self. These results highlight that a major area underpinning experiences of diabetes distress is not feeling in control.Conclusions: Consideration should be given to how psychological factors, such as locus of control and learned helplessness, may constitute underlying mechanisms impacting emotional regulation in those experiencing diabetes distress. Clinicians should consider including and leading discussions around distress during appointments, as well as using approaches that promote patient autonomy and empowerment.