In patients with diabetes, depression was found to be linked with worse cognition and higher dementia risk. The potential mitigating impact of antidepressant treatment is unclear.

• This systematic review and meta- analysis included observational studies that assessed the relationship between depression and cognition, mild cognitive impairment or dementia in patients with diabetes.

• Meta-analyses (with 10 out of 19 included articles) revealed greater declines in executive function (standardized mean difference [SMD]=-0.39), language (SMD=-0.80), memory (SMD=-0.63) and overall cognition (SMD=-0.77) as well as a greater dementia risk (HR=1.82) in patients with diabetes and depression, vs those with diabetes only.

• For complex attention, no significant differences were found.