Tau protein level as a cognitive impairment marker in diabetes mellitus

M.V. Matveeva¹, Yu.G. Samoilova¹, N.G. Zhukova¹, D.A. Kudlay²

¹Siberian State Medical University, Tomsk

²NRC Institute of Immunology, Moscow

Diabetes mellitus (DM) is a polyetiological metabolic disease accompanied by systemic damage to organs, including the central nervous system. Clinically, these changes are associated with cognitive impairment, the pathogenesis of which is also largely heterogeneous.

Aim: to assess the tau protein role in the cognitive impairment diagnosis in patients with type 1 and type 2 DM.

Patients and Methods: the study was approved by the Ethics Committee. All patients signed informed consent. The study design was observational, cross-sectional and snapshot. It included 63 patients with type 1 DM, whose average age was 29.1±8.5 years, and the control group of 25 subjects matched for sex and age. In addition, 102 patients with type 2 DM at the age of 60.8±11.9 years were also recruited, whereas the control group consisted of 20 subjects matched by sex and age. Patients underwent the evaluation for blood glucose, glycated hemoglobin (HbA1c), and tau protein levels. Cognitive functions were tested using the Montreal Cognitive Assessment (MoCA). To assess glucose variability, glycemia continuous monitoring was performed with coefficients estimated.

Results: patients with type 1 and type 2 DM had cognitive impairment (25.5 (24–27) and 21.3 (19–24)) points, according to MoCA test. The impairment clinical spectrum varied depending on the DM type.  When assessing the tau protein level, a significant increase in its content was registered among patients with type 1 and type 2 DM (p=0.001, U=113.0; p=0.001; U=11.0). Correlation analysis showed a moderate positive association of tau protein level with fasting glycemia levels (r=0.6, p<0.001), glycated hemoglobin (r=0.5, p<0.001), and high positive association — with MoCA test (r=0.9, p<0.001). Adding that, in the group with type 2 DM, a weakly positive association was found between the tau protein level and the presence of cognitive impairments (r=0.2, p<0.001), and strong positive association — with the age of patients (r=0.8, p<0.001). Significant associations in coefficients of variation and associations with tau protein level were found only in the group with type 1 DM.

Conclusion: in DM, cognitive impairments development is associated with tauopathy and chronic hyperglycemia.

Keywords: diabetes mellitus, hyperglycemia, tau protein, cognitive  impairments, tauopathy.

For citation: Matveeva M.V., Yu.G. Samoilova, Zhukova N.G., Kudlay D.A. Tau protein level as a cognitive impairment marker in diabetes mellitus. RMJ. 2019;4:50–53.