Cognitive Performance in Middle-Aged Adults with Type 2 Diabetes: Normative Comparisons and Associations with Medical and Psychological Variables

OBJECTIVE: This study examined whether middle-aged individuals with type 2 diabetes mellitus (T2DM) without major comorbidities perform comparably to normative samples on a comprehensive neuropsychological test battery. The study also investigated which medical, psychological, or demographic factors are associated with cognitive performance in this population. METHOD: Forty-eight middle-aged Finnish adults with T2DM completed a fixed neuropsychological test battery covering core cognitive domains. Z-scores were calculated for each test and cognitive domain using published normative data. Global and domain-specific performance was compared to normative expectations. Bivariate correlations were computed to examine associations with medical, psychological, and background variables. RESULTS: The cognitive performance of patients was broadly consistent with normative expectations, and the proportion of individuals with below-average scores in each domain did not exceed proportions expected based on normative distributions. No consistent or strong associations were found between cognitive performance and any medical or demographic variable. Psychological symptoms, especially fatigue and anxiety symptoms, were significantly associated with the presence of subjective cognitive complaints but not with objective neuropsychological test scores. CONCLUSIONS: Cognitive performance in middle-aged individuals with T2DM and no severe complications appears comparable to normative samples. The absence of associations with metabolic risk factors may reflect a preclinical stage before measurable cognitive decline emerges. Limited statistical power and use of non-local normative data should be considered when interpreting the findings. Overall, the results highlight middle age as a potential window for preventive efforts.