This systematic review and meta-analysis aimed to systematically summarize prospective data on the relationship between diabetes and cognitive decline. The study included 25 longitudinal studies that assessed cognitive function in individuals with diabetes at baseline and follow-up. The results showed that individuals with diabetes had a 1.2 to 1.5-fold greater rate of cognitive decline compared to those without diabetes. Specifically, the Mini-Mental State Exam (MMSE) and Digit Symbol Substitution Test (DSS) indicated that diabetes increased the odds of cognitive decline by 1.2-fold (95% CI 1.05–1.4) and 1.7-fold (95% CI 1.3–2.3), respectively. Additionally, the odds of developing dementia were 1.6-fold higher (95% CI 1.4–1.8) in individuals with diabetes. The review highlights that diabetes is a significant risk factor for cognitive decline and dementia, emphasizing the need to include cognitive function assessments in future studies of diabetes management.This systematic review and meta-analysis aimed to systematically summarize prospective data on the relationship between diabetes and cognitive decline. The study included 25 longitudinal studies that assessed cognitive function in individuals with diabetes at baseline and follow-up. The results showed that individuals with diabetes had a 1.2 to 1.5-fold greater rate of cognitive decline compared to those without diabetes. Specifically, the Mini-Mental State Exam (MMSE) and Digit Symbol Substitution Test (DSS) indicated that diabetes increased the odds of cognitive decline by 1.2-fold (95% CI 1.05–1.4) and 1.7-fold (95% CI 1.3–2.3), respectively. Additionally, the odds of developing dementia were 1.6-fold higher (95% CI 1.4–1.8) in individuals with diabetes. The review highlights that diabetes is a significant risk factor for cognitive decline and dementia, emphasizing the need to include cognitive function assessments in future studies of diabetes management.