This systematic review of prospective observational studies found that individuals with diabetes had a 1.2- to 1.5-fold greater change in cognitive function over time compared to those without diabetes. The Mini-Mental State Exam (MMSE) and Digit Symbol Substitution Test (DSS) showed that diabetes increased the odds of cognitive decline by 1.2-fold and 1.7-fold, respectively, and the odds of future dementia by 1.6-fold. These findings suggest that diabetes is associated with a greater rate of cognitive decline and increased risk of dementia. The review highlights the need to include cognitive dysfunction as a chronic complication of diabetes. The studies included in the review were prospective, longitudinal, and assessed cognitive function at baseline and follow-up. The results were pooled and analyzed using statistical methods to estimate the magnitude of the risk of cognitive dysfunction in people with diabetes. The review also identified potential limitations, such as the exclusion of cognitively impaired individuals at baseline and the lack of information on those who died or were lost to follow-up. Despite these limitations, the results consistently showed a significant association between diabetes and cognitive decline. The review also discussed possible mechanisms linking diabetes to cognitive decline, including cerebrovascular disease, depression, hypoglycaemia, and hyperglycaemia. The findings suggest that cognitive dysfunction should be considered as a chronic consequence of diabetes and that future studies should include cognitive function assessments to determine whether cognitive decline can be mitigated.This systematic review of prospective observational studies found that individuals with diabetes had a 1.2- to 1.5-fold greater change in cognitive function over time compared to those without diabetes. The Mini-Mental State Exam (MMSE) and Digit Symbol Substitution Test (DSS) showed that diabetes increased the odds of cognitive decline by 1.2-fold and 1.7-fold, respectively, and the odds of future dementia by 1.6-fold. These findings suggest that diabetes is associated with a greater rate of cognitive decline and increased risk of dementia. The review highlights the need to include cognitive dysfunction as a chronic complication of diabetes. The studies included in the review were prospective, longitudinal, and assessed cognitive function at baseline and follow-up. The results were pooled and analyzed using statistical methods to estimate the magnitude of the risk of cognitive dysfunction in people with diabetes. The review also identified potential limitations, such as the exclusion of cognitively impaired individuals at baseline and the lack of information on those who died or were lost to follow-up. Despite these limitations, the results consistently showed a significant association between diabetes and cognitive decline. The review also discussed possible mechanisms linking diabetes to cognitive decline, including cerebrovascular disease, depression, hypoglycaemia, and hyperglycaemia. The findings suggest that cognitive dysfunction should be considered as a chronic consequence of diabetes and that future studies should include cognitive function assessments to determine whether cognitive decline can be mitigated.