Risk  of Dementia in Diabetes
Both type 1 and type 2 diabetes mellitus are associated with cognitive performance impairments. In type 1 diabetes mellitus this is reflected in a mild to moderate slowing of mental speed and a diminished mental flexibility.¹ In type 2 diabetes cognitive changes mainly affect learning and memory, mental flexibility and mental speed.^2,3 Longitudinal population-based studies indicate that the rate of cognitive decline is accelerated in elderly subjects with type 2 diabetes.⁴ While the association between diabetes and these modest changes in cognition is now well established; the relationship between diabetes and dementia has been subject of debate.

Early studies on the relationship between diabetes and dementia suggested that: “diabetes and Alzheimer’s disease may not co-exist”.⁵ This suggestion was based on the observation that the prevalence of diabetes among patients with established Alzheimer’s disease was low. It is likely, however, that these early studies suffered from methodological limitations such as survival bias. Moreover, the possible effects of Alzheimer’s disease itself on glucose metabolism may have confounded the results.