Abstract: Objective To evaluate early occult brain functional damage in patients with type 2 diabetes mellitus using
resting-state functional magnetic resonance imaging (MRI). Methods High-resolution three-dimensional T1-weighted fast
spoiled gradient recalled echo MRI and resting-state functional MRI images were obtained from 18 patients with type 2
diabetes mellitus and 18 normal control subjects. Regional homogeneity (ReHo) map, amplitude of low-frequency fluctuation
(ALFF) map, and functional connectivity map of the bilateral hippocampus and posterior cingulate gyrus were calculated and
voxel-based analysis was performed using two-sample t-test. Results In type 2 diabetic patients, decreased ReHo was deteted
in the right thalamus, hippocampus, olfactory cortex and left putamen as compared with the normal controls. The decreased
ALFF was found mainly in the left middle frontal gyrus, right supramarginal gyrus and middle occipital gyrus in the diabetic
patients. The patients showed reduced functional connectivity between the bilateral hippocampus but not between the
bilateral posterior gyrus and the other brain regions. Conclusion The occult brain damage is featured by decreased ReHo and
ALFF in multiple brain regions and reduced functional connectivity between the bilateral hippocampus in type 2 diabetic
patients.