Objective      To determine the effect of type 2 diabetes mellitus (T2DM) on the cognitive function of  middle-aged patients and its characteristics.       Methods      All subjects admitted in the outpatient department from December 2013 to June 2015 were screened by

the mini-mental state examination (MMSE) and activity of daily living scale (ADL)

and only 52 45- to 65-year-old patients with former score 24 and later score 23 were recruited in this study. These patients were assigned as DM group

and 52 healthy volunteers with matched age

sex and education level were enrolled as HC group. Montreal cognitive assessment (MoCA)

auditory verbal learning test

digit span test and verbal fluency test were applied to examine the cognitive function in the 2 groups. T

2

WI

fluid attenuated inversion recovery (FLAIR) and 3D-T

1

WI MRI data were collected by Siemens 3.0T MR scanner. The white matter lesions were evaluated by FreeSurfer software

and the volumes of white and grey matter were evaluated with VBM8 and statistical analysis.       Results      The DM group had obviously decreases in MoCA

DST (back) and TMT-B rating scores than the HC group (P0.05). The MocA score was significantly lower in the DM patients with diabetic retinopathy than those without (P0.05). There were no differences in the MoCA

MMSE and TMT-B rating scores between the HbA1c≤7% DM patients and the HC group (P0.05). But remarkable difference was seen in the TMT-B rating score in the HbA1c7% patients with the HbA1c≤7% patients and HC group (P0.05). The DM group had reduced gray matter volume in the medial frontal gyrus than the HC group (false discovery rate correction

P0.05

cluster volume 100 voxels).       Conclusion      T2DM induces cognitive impairment in middle-aged T2DM patients

with main manifestations of decreased abilities to execute

attention

and short-term memory. The patients accompanied with diabetic retinopathy have more severe cognitive impairment.