Markers of cognitive impairment in patients with type 2 diabetes

Background. The study aimed to evaluate the correlations of cognitive function with metabolic, nutritional, hormonal and immunologic parameters in patients with type 2 diabetes (T2D), in order to identify markers of cognitive impairment.

Material and methods. This cross-sectional study included 216 T2D patients and 23 healthy individuals (HC). The cognitive status was evaluated by the MoCA test. From HC and 145 T2D patients several parameters were also determined: C-peptide, vitamin B12, high-sensitivity CRP (by chemiluminescent immunometric assay), HbA1c, lipids, cortisol, TSH, Mg (by a Cobas 6000 analyzer), glucose (by glucose-oxidase method) and leptin and adiponectin (by ELISA method). Statistical significance was set at p < 0.05.

Results. There was a significant difference in the MoCA scores between HC and T2D groups (26.0(17.0-29.0) vs. 23.0(13.0- 31.0) points; p: 0.004). T2D patients with cognitive dysfunction were significantly older and less formally educated (p < 0.0001). Age negatively correlated with MoCA scores (-0.31; 95%CI:-0.42,-0.18; p < 0.0001). T2D patients had significantly lower visuospatial/executive (4.0(0.0-5.0) vs. 5.0(2.0-5.0) points; p: 0.04) and delayed recall scores (2.0(0.0- 5.0) vs. 3.0(1.0-5.0) points; p: 0.03) and lower serum Mg concentrations (0.81(0.12-0.99) vs. 0.92(0.41-1.35) mmol/l, p < 0.0001). Serum Mg levels positively correlated with MoCA scores (0.24, 95%CI: 0.07, 0.39; p: 0.003) and with visuospatial/ executive (0.30; 95%CI: 0.14, 0.45; p: 0.0002) and naming functions (0.18; 95%CI: 0.01, 0.34; p: 0.02).

Conclusions. Patients with T2D had significant cognitive impairment, with decrements in the visuospatial/executive and delayed recall domains. Younger age and higher education correlated with better cognitive function. Serum Mg levels correlated positively with overall cognitive function and with visuospatial/executive and naming domains.