Depression comorbidity in children and adolescents with type 2 diabetes mellitus: a systematic review and meta-analysis

Background Depression is a frequent psychological comorbidity among youth with type 2 diabetes mellitus (T2DM), yet reported prevalence rates vary widely across studies. This meta-analysis aimed to estimate the pooled prevalence of depression and explore sources of heterogeneity. Methods This meta-analysis is registered with PROSPERO (CRD420251126166). We systematically searched PubMed, Embase, Web of Science, Cochrane Library, CINAHL, and PsycINFO from inception to October 24, 2025. The pooled prevalence was calculated using a random-effects model. Subgroup analyses and meta-regression were conducted to investigate potential sources of heterogeneity. All processes of study screening, data extraction, and quality assessment were carried out independently by two researchers. Results Seventeen studies comprising 5,215 participants were included. The pooled prevalence of comorbid depression was 23.1% (95% CI: 18.0%–29.1%), with substantial heterogeneity (I² = 93%). Subgroup analyses indicated that prevalence differed significantly by HbA1c level and assessment method. Participants with HbA1c < 7% showed higher prevalence (52.0%) than those with HbA1c ≥ 7% (24.0%). Studies using self-report scales reported higher prevalence (25.2%) than those using clinical diagnostic criteria (12.2%). Univariate meta-regression indicated that both HbA1c level and the depression assessment method significantly influenced the reported prevalence of depression. Conclusions Approximately one in four youth with T2DM experience depression. Variations in assessment method and glycemic control may contribute to the heterogeneity of reported prevalence. These findings underscore the importance of standardized diagnostic procedures and early psychological screening in pediatric T2DM populations to improve both mental health and diabetes outcomes. Systematic review registration https://www.crd.york.ac.uk/prospero/ , identifier CRD420251126166