Background: There is debate over the relationship between diabetes and the main forms of dementia. The cognitive alterations associated with type 2 diabetes (T2D) mostly impact mental flexibility, mental speed, and learning and memory.
 Objectives: To ascertain the degree of the link between diabetes and dementia, we thoroughly reviewed papers on the incidence of dementia in individuals with diabetes mellitus in this study.
 Methods: PubMed, SCOPUS, Web of Science, and Science Direct were systematically searched for relevant literature. Rayyan QRCI was employed throughout this comprehensive process.
 Results and Interpretation: We included ten studies with a total of 173797 participants, and 78828 (45.4%) were males. All of the included studies were prospective cohorts. For diabetic patients, early-onset diabetes, poor glycemic management, and diabetes status are risk factors for dementia development. There was also a higher chance of dementia development in those with mild to severe motor cognitive impairment and hereditary variables. Longitudinal studies that involve comprehensive evaluations of comorbid diseases and diabetes-related variables, as well as rigorous assessments of cognition—ideally in conjunction with neuroimaging—will be necessary for this process. This method will work best with large population-based cohort studies of older adults with diabetes and with longitudinal studies of at-risk groups that look at the development of diabetes, metabolic syndrome, vascular disease, and cognitive decline.