The characteristic of cognitive function in Type 2 diabetes mellitus

•Our results showed impaired performance in MMSE, Trails B, digit span and block design.•T2DM should be considered to be a risk factor for cognitive impairment in elderly.•Diabetic-related factors may associate with the risk of cognitive impairment in T2DM.

AimTo identify characteristics of neuropsychological function among elderly individuals with Type 2 diabetes mellitus with mild cognitive impairment (T2DM-MCI) and evaluate domain-specific effects of T2DM on cognition.MethodsThis was a cross-sectional study conducted in Tianjin, China. MCI subjects (n = 246) and controls were identified in elderly individuals with diabetes, and groups were matched in a 1:1 ratio for sex, age and educational level. Cognitive function was assessed using WAIS-III (block design, digit span), Trail Making Test A, Trail Making Test B, WMS-III (word list learning, logical memory), verbal fluency and MMSE. We used multivariable logistic regression to find diabetic factors associated with MCI.ResultsThe mean MMSE score was 22.73 ± 2.32 in subjects with T2DM-MCI, versus 26.71 ± 2.43 in subjects cognitive normal (P < 0.001). Executive and visuospatial functions were more impaired in individuals with T2DM-MCI than in those without, as assessed using block design (P < 0.001), digit span test (P < 0.001), and Trails B (P < 0.001). For memory, subjects with T2DM-MCI did worse than those cognitive normal on the word learning list delayed recall (P = 0.015). Diabetic-related factors such as longer duration of T2DM, higher HbA1c, insulin treatment was associated with a lower level of cognitive functioning using MMSE, block design, delayed recall and Trails B test.ConclusionsT2DM should be considered a risk factor for MCI. This risk may be associated with duration of diabetes, use of glucose-lowering medications, degree of glucose control. To decrease risk of MCI, it is important to monitor glucose control and adjust medications appropriately in elderly patients.