Association Between Depression and Medication Adherence Among Patients with Diabetes Mellitus: A Systematic Review

Abstract

Background: Diabetes mellitus (DM) is a major global public health concern affecting more than 500 million individuals worldwide. Effective diabetes management depends heavily on adherence to prescribed medication regimens, lifestyle modifications, and regular monitoring of blood glucose levels. Depression is one of the most common psychiatric comorbidities among individuals with diabetes and has been associated with poor treatment outcomes. The coexistence of diabetes and depression creates significant challenges for disease management, often resulting in decreased medication adherence, poor glycemic control, increased risk of complications, and reduced quality of life. Despite growing evidence on the relationship between depression and treatment adherence, findings remain dispersed across various healthcare settings and populations. Objective: This systematic review aimed to examine the association between depression and medication adherence among patients with diabetes mellitus and to identify factors influencing this relationship. Methods: A systematic literature review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Electronic databases including PubMed, Scopus, Web of  Science, CINAHL, PsycINFO, and Google Scholar were searched for studies published between 2010 and 2025. Studies investigating depression and medication adherence among adults with Type 1 or Type 2 diabetes mellitus were included. Data were extracted regarding study design, sample characteristics, depression assessment tools, adherence measures, and key findings. Results: Most studies demonstrated a significant inverse relationship between depression and medication adherence. Patients with moderate to severe depressive symptoms consistently reported lower adherence to antidiabetic medications compared to non-depressed individuals. Depression was associated with poor self-care behaviors, higher HbA1c levels, increased hospitalization, and greater risk of diabetes-related complications. Several studies highlighted the effectiveness of integrated care interventions in improving both depression outcomes and medication adherence. Conclusion: Depression significantly affects medication adherence among individuals with diabetes mellitus. Routine screening for depression and integrated psychosocial interventions are essential components of comprehensive diabetes care..