Objective: To explore the cortical thickness changes in the patients with type 2 diabetes mellitus and the effects of the insulin therapy on the brain using whole brain cortical thickness mapping.
Methods: High resolution three-dimensional T1-weighted fast spoiled gradient recalled echo MRI images were obtained from 11 normal controls and 11 patients with type II diabetes at baseline level (before insulin therapy) and follow-up level (after insulin therapy for 1 year). The whole brain cortical thickness map was calculated by the closest point methods.The cortical thickness of each brain region was calculated using the automatic region of interest. The paired t test was performed for the mean cortical thickness.
Results: The mean cortical thickness of bilateral hemisphere and whole brain was decreased in the patients with type 2 diabetes mellitus compared with normal controls (P < 0.05).After insulin therapy 1 year, the mean cortical thickness of right hemisphere and whole brain at follow-up was significantly increased compared with that at baseline (P < 0.05), and the mean cortical thickness of left hemisphere showed no significant difference between baseline and follow-up (P > 0.05). Mean cortical thickness over each brain region demonstrated that increased cortical thickness were mainly located in the left medial orbitofrontal gyrus, bilateral pars opercularis, right supramarginal gyrus, right lateral occipital gyrus, left calcarine gyrus, right fusiform gyrus, bilateral inferior temporal gyri, middle temporal gyri, left caudal anterior cingulate, bilateral entorhinal cortex, left parahippocampal cortex, right insular lobe and right rostral anterior cingulate.
Conclusion: Cortical thinning was investigated in the patients with type 2 diabetes mellitus compared with normal controls, and wide cortical thickening was demonstrated after insulin therapy for 1 years.The precise mechanism should be further explored.