AIMS: This study evaluated the effectiveness of cognitive-behavioural therapy (CBT) in managing comorbid depression and diabetes by examining its influence on psychological and metabolic outcomes, addressing inconsistencies in existing research. METHODS: A systematic review of 26 randomized controlled trials (RCTs) involving 4220 participants conducted between 2000 and 2024 was performed. Subgroup analyses evaluated geographic location, delivery modes, and intervention characteristics, including session duration and frequency. RESULTS: CBT significantly reduced depressive symptoms (SMD = -1.30, 95 % CI -2.46 to -0.13, p <
0.05), demonstrating substantial psychological benefits. Its effect on glycemic control, measured by HbA1c levels, was modest and not statistically significant (SMD = -0.56, 95 % CI -1.12-0.01, p >
0.05). Subgroup analyses revealed variations based on region and intervention characteristics. High heterogeneity across studies highlighted the need for tailored approaches that consider context-specific factors and delivery methods. CONCLUSIONS: CBT effectively reduces depressive symptoms in individuals with diabetes, supporting its role in integrated care models. However, its association with glycemic control remains inconclusive. Future research should refine CBT protocols to enhance both psychological and metabolic outcomes while addressing diverse needs.