A Surface-based Cerebral Structural And Functional MRI Study In Type 2 Diabete Mellitus Patients With Or Without Insulin Resistance

Objective This study is to explore the alterations of the cerebral cortical structure and function in type 2 diabete mellitus(T2DM)patients with with or without insulin resistance by used surface-based magnetic resonance imaging(MRI),and analyze its correlation with clinical data and neuropsychological scale scores,so as to explore the vulnerable brain regions and potential neurophysiological mechanism of insulin resistance in T2 DM patientsSubjects A total of 111 T2 DM patients admitted to the Endocrine Diagnosis and Treatment Center of Gansu Provincial Hospital from October 2020 to October 2022 were prospectively collected.According to HOMA2-IR ≥ 1.4,T2 DM patients were divided into 40 T2 DM patients with IR(termed T2DM-IR)and 71 T2 DM patients without IR(termed T2 DMn IR).During the same period,50 healthy controls(HCs),matched with T2 DM patients in gender,age,and education level,were recruited from the community near the hospital and the health examination center of Gansu Provincial Hospital.Collected clinical data of all subjects,evaluated cognitive function,depression and anxiety.Cerebral structural and functional images of all subjects were obtained by 3.0T MRI.Using DPABISurf_V1.6 and SPSS 25.0 software performed data preprocessing and statistical analysis to calculate the differences in cortical structural characteristic indicators(volume,thickness,surface area,sulcus depth,and curvature)among the three groups.The brain regions with statistically different cortical structural characteristic indicators were selected as regions of interest,and cortical functional indicators(fractional amplitude of low-frequency fluctuation,regional homogeneity,degree centrality)were extracted and compared among groups.Then correlation analysis was further performed between cortical structural characteristics,functional indicators,and clinical data(biochemical indicators,fasting glucose,fasting insulin,HOMA2-IR,etc.),as well as neuropsychological scale scores in different brain regions.Results Compared with HCs,the depression scores were significantly increased in the T2 DM patients,the bilateral insular cortex and the right inferior frontal gyrus was significantly atrophied in all T2 DM patients,the right insular cortex and inferior frontal gyrus atrophied more significantly in T2DM-IR than in T2DM-n IR group.In particular,compromised left insular cortex was accompanied by functional abnormality of spontaneous brain activity.In addition,compared with HCs,the thickness of right paracentral lobule,the thickness and volume of right postcentral cortex increased in T2 DM patients.The T2DM-IR and T2DM-n IR groups showed negative correlations between the cortical thickness of the left insular and fasting glucose(r =﹣0.247,P = 0.009,PFDR = 0.012),the cortical thickness of the right insular and HAMD-24 scores(r =﹣0.294,P = 0.009,PFDR = 0.012),the volume of the inferior frontal gyrus and fasting insulin levels(r =﹣0.196,P = 0.04,PFDR = 0.04),and the right paracentral lobule and high-density lipoprotein levels(r =﹣0.249,P = 0.009,PFDR = 0.012).Conclusion Our results suggested that the bilateral insular cortex is the core region linked to T2 DM,and the inferior frontal gyrus is sensitive to insulin resistance in T2 DM patients.Our study provides new insights into the neuropathological mechanism of cerebral cortex impairment in T2 DM patients with or without insulin resistance,and provides potential neuroimaging targets for early intervention of T2DM-IR patients.