Meta-analysis finds 23% subthreshold depression prevalence in patients with diabetes mellitus

AIMS: Subthreshold depression has low clinical recognition, but increases patients' risk of complications and impairs their quality of life. This study aimed to systematically review the literature to determine the prevalence of subthreshold depression in patients with diabetes mellitus and compare rates across countries, gender, settings and study designs. DESIGN: This was a systematic review and meta-analysis of cross-sectional and cohort studies. METHODS: We searched nine databases (PubMed, PsyclNFO, CINAHL, The Cochrane Library, EMbase, Web of Science, China Knowledge Resource Integrated Database (CNKI), Chinese Biomedical Database (CBM) and Wanfang) to 15 February 2026. Meta-analysis was performed using the Stata 16.0 software package, and the prevalence of each study report was combined based on a random-effect model. Subgroup analyses were performed. RESULTS: In total 2564 articles were retrieved, of which 33 met the inclusion criteria for meta-analysis, involving 255 371 participants. The pooled prevalence of subthreshold depression in patients with diabetes mellitus was 23.0% (95% CI: 20.0%-26.0%, I = 99.2%, p < 0.001). Subgroup analyses revealed higher prevalence in developing countries (26.6%), females (16.0%), cross-sectional studies (24.5%) and patients in hospital (24.5%). CONCLUSIONS: The findings highlight overall high rates but also substantial disparities in the prevalence of subthreshold depression in patients with diabetes mellitus across demographics and settings, with elevated rates in developing nations and female patients. Findings suggest enhanced screening and interventions should target high-risk groups and underscore the importance of addressing mental health in diabetes management, particularly in resource-limited settings and among vulnerable populations. Review Registration PROSPERO: CRD42024615241.