Background: Evidence suggests that reminiscence therapy can effectively reduce cognitive and psychological symptoms. This study was conducted to examine the effect of individual reminiscence therapy on cognitive level, quality of life and depressive symptoms in older adults with type 2 diabetes. Methods: This study is an experimental type, randomised controlled study designed in pre-test – post-test design. The sample size of the study consisted of 58 older adults with type 2 diabetes, consisting of 29 intervention and 29 control subjects. The older adults in the intervention group were individually subjected to 5 weeks of reminiscence therapy in two sessions (each session 40–45 min) per week. No intervention was applied to the control group. Personal Information Form, Standardised Mini Mental Test, SF-36 Quality of Life and Beck Depression Inventory were used to collect the data. Results: While there was no significant difference between the pre-test Mini Mental Test, Beck Depression Inventory total score and SF-36 Quality of Life Scale mental and physical health sub-dimension mean scores of the older adults in the intervention group and the mean scores of those in the control group (P > 0.05), the difference between the Mini Mental Test, Beck Depression Inventory total score and SF-36 Quality of Life Scale mental and physical health sub-dimension mean scores of the older adults in the intervention and control groups in the post-test was found to be statistically significant (P < 0.05). The post-test Mini Mental Test total score, SF-36 Quality of Life Scale mental and physical health sub-dimension mean scores of the older adults in the intervention group were higher than the older adults in the control group. It was determined that the post-test Beck Depression Inventory total mean scores of the older adults in the intervention group were lower than the older adults in the control group. Conclusion: Reminiscence therapy can positively affect cognitive levels, quality of life and depression symptoms of older adults living in the community. Individual reminiscence therapy can be used as a nursing intervention in primary healthcare.