Abstract

Background and Aims: Insulin degrading enzyme (IDE) contributes to the degradation processes of insulin and Aβ. We aimed to investigate the role of IDE in type 2 diabetes patients with mild cognitive impairment (MCI).

Methods: A total of 146 individuals with type 2 diabetes were enrolled and divided into two groups according to the Montreal Cognitive Assessment (MoCA) score. Demographic characteristics, cognitive function and serum IDE level were examined.

Results: There were 75 patients with MCI and 71 patients without MCI. Diabetic patients with MCI had a higher serum level of IDE compared with the control group (p < 0.001). Among patients with MCI, serum IDE level was positively correlated with the MoCA score (r = 0.839; p < 0.001). Correlation analysis demonstrated that IDE was positively correlated with MoCA score (r = 0.815; p < 0.001) but negatively correlated with the Trail Making Test-B (r = −0.413; p < 0.001), fasting blood-glucose (r = −0.372; p < 0.001), glycosylated hemoglobin (r = −0.214; p = 0.015), homeostasis model of assessment for insulin resistance (r = −0.560; p < 0.001) and the mean amplitude of glycemic excursions (r = −0.551; p < 0.001) in all subjects. In logistic regression analysis for MCI, IDE (p = 0.010) was an independent variable, after adjusting for age, sex, education, liver function, kidney function, and lipid levels.

Conclusion: This study demonstrated a greater likelihood of MCI with decreasing serum IDE in patients with type 2 diabetes.

Keywords: Homeostasis model of assessment for insulin resistance, insulin degrading enzyme, mild cognitive impairment, the mean amplitude of glycemic excursions, the Trail Making Test-B, Type 2 diabetes.