The aim of this manuscript is to provide a brief review of the link between diabetes mellitus with cognitive impairment, the possible pathophysiology linking the two, and some possible therapeutic interventions for the treatment of this condition. The prevalence of diabetes increases with age, so also dementia increases in later life. As the population ages, type 2 diabetes and AD are increasing. Both diseases are chronic and are the leading causes of morbidity and mortality. Recent studies showed that older people with type 2 diabetes have a higher risk of cognitive decline. The precise mechanism linking the two remains to be found out. Several hypothetical mechanisms have been postulated. Type 2 diabetes is a risk factor for AD and vascular dementia. The association between diabetes and AD is particularly strong among carriers of the APOE ε4. Several studies have linked dementia to diabetes. Impaired fasting glucose and impaired glucose tolerance and insulin resistance have also been associated with poor cognitive performance and at risk of developing cognitive impairment. Studies have suggested that metabolic syndrome may be linked to vascular dementia, while contrasting findings showed the role of metabolic syndrome to AD. In this review, how diabetes and cognitive impairment and Alzheimer’s disease are mutually linked, possible mechanism linking the two and some possible therapeutic interventions with some patents that seem to be good therapeutic targets in future are discussed.