Effects of prediabetes and type 2 diabetes on cognitive functions

Introduction We aimed to investigate the effect of glycemic impairment in prediabetes on cognitive impairment and the impact of glycemic control on cognitive function in patients with diabetes. Materials and methodsThis age- and sex-matched case-control study included a total of 80 individuals: 20 patients with prediabetes, 20 patients with well-controlled type 2 diabetes mellitus (T2DM) (HbA1C < %7.5), 20 patients with poorly controlled T2DM (HbA1C >% 7.5), and 20 healthy controls. Results The poorly controlled T2DM patients performed significantly worse than controls and patients with prediabetes in the verbal memory process test (p = 0.041). In Trail Making Test B, the well-controlled and poorly-controlled groups with diabetes performed significantly worse (p = 0.015) than patients with prediabetes and controls, and in the Wisconsin Card Sorting Test (WCST), all three patient groups performed significantly worse (p = 0.007) than controls. Conclusion T2DM causes early brain aging and declines cognitive functions since the prediabetic stage. Poor glycemic control in T2DM patients contributes to cognitive impairments, especially in learning.