The Impact of Mental Health Disorders on Mortality Rates in Patients with Type 2 Diabetes Mellitus (Systematic Literature Review)

Abstract* Background Type 2 diabetes mellitus (T2DM) is a major global health burden with high mortality. Comorbid mental health disorders, including depression, anxiety, and severe mental illness (SMI), are reported to worsen metabolic control and elevate mortality risk, yet findings remain inconsistent across countries and study designs. Objective: This review systematically examines the association between mental health disorders and mortality among patients with T2DM. Methods Following PRISMA guidelines, systematic searches were conducted across Scopus, ProQuest, Cochrane Library, ScienceDirect, PubMed, and EBSCO, yielding 3,494 records. Seventeen studies published between 2020 and 2025 met inclusion criteria. Eligible designs included prospective and retrospective cohorts, cross-sectional, and nested case-control studies, with sample sizes ranging from 146 to 875,671 participants. Outcomes assessed were all-cause mortality, cardiovascular mortality, and suicide. Results Depression was the most frequently examined disorder, associated with hazard ratios (HR) for all-cause mortality between 1.40 and 2.47. SMIs such as schizophrenia and bipolar disorder showed greater risks, with HRs up to 2.24 for cardiovascular mortality. Suicide risk was significantly higher, particularly in schizophrenia (HR 2.51) and bipolar disorder (HR 3.00). Anxiety was also linked to increased mortality, though with smaller effect sizes. Risk varied by age, sex, and healthcare access. Conclusion Mental health disorders are consistently associated with excess mortality in patients with T2DM. These findings point out the need for integrated care models that address both physical and mental health to reduce mortality in this vulnerable population.