Cognitive Function Deficits Associated With Long-Duration Type 1 Diabetes and Vascular Complications

Patients with type 1 diabetes now live long enough to experience cognitive decline. During middle age, they show mild cognitive deficits, but it is unknown whether severity increases with aging or whether cognitive profiles are similar to those of age-matched peers with and without diabetes.

We tested and compared cognition in 82 individuals with 50 or more years of type 1 diabetes (Medalists), 31 age-matched individuals with type 2 diabetes, and 30 age-matched control subjects without diabetes. Medical histories and biospecimens were collected. We also evaluated the association of complications with cognition in Medalists only.

Compared with control subjects, both individuals with type 1 diabetes and individuals with type 2 diabetes performed worse on immediate and delayed recall (P ≤ 0.002) and psychomotor speed in both hands (P ≤ 0.01) and showed a trend toward worse executive function (P = 0.05). In Medalists, cardiovascular disease was associated with decreased executive function and proliferative diabetic retinopathy with slower psychomotor speed.

Both patients with type 1 and patients with type 2 diabetes showed overall worse cognition than control subjects. Further, in Medalists, a relationship between complications and cognition was seen. Although both groups with diabetes showed similar deficit patterns, the underlying mechanisms may be different. Now that patients with type 1 diabetes are living longer, efforts should be made to evaluate cognition and to identify modifying behaviors to slow decline.