Cognitive Function Is Impaired in Recently Diagnosed Type 2 Diabetes, but Not in Type 1 Diabetes

Diabetes associates with higher risk of dementia. We hypothesized that cognitive function is already impaired during the early course of diabetes. Thus, we performed a cross-sectional analysis within the German Diabetes Study including patients within the first year after diagnosis of type 1 (n=82) or type 2 (n=119) diabetes, patients with type 1 (n=45) or type 2 (n=65) diabetes five years after study inclusion and metabolically healthy humans (n=42). Participants underwent comprehensive metabolic phenotyping and testing of different domains of cognitive function. Cognition test outcomes were compared using linear regression models with age, sex, and crystallized intelligence as independent variables. Furthermore, within the groups, associations between cognitive function and age, sex, body mass index (BMI), insulin sensitivity, high-sensitivity C-reactive protein, hemoglobin A1c, and crystallized intelligence were studied using linear regression analysis. In participants with recently diagnosed diabetes, verbal memory was poorer in patients with type 2 diabetes (P=0.029), but not in type 1 diabetes (P=0.154) when compared to healthy individuals. Five years after diagnosis, type 2 diabetes patients also showed decreased verbal memory than those with type 1 diabetes (P=0.013). In addition to crystallized intelligence, a higher BMI among individuals with recently diagnosed type 2 and male sex among individuals with recently diagnosed type 1 diabetes were associated with impaired verbal memory (all P