Objective To explore early aberrant change of the function and grey matter volume within default-mode network in patients with type 2 diabetes mellitus (T2DM) by Independent component analysis and voxel-based morphometry.Methods Twenty-nine T2DM patients and thirty-three healthy control subjects were recruited in this study between May 2014 and January 2015,and the demographic and clinical data (fasting plasma glucose and HbA1c level) were obtained.General cognition was assessed by MMSE and MoCA in all subjects.Resting-state fMRI and T1-weighted imaging were performed in all subjects.Then the z-maps of default-mode network were obtained from Resting-state fMRI by independent component analysis,and the grey matter volumes were extracted by VBM.Finally,two-sample t-test was performed in the function and grey matter volume of DMN between two groups,and pearson correlation coefficients among zFC values extracted from significantly different brain regions,grey matter volumes and durations of T2DM patients were calculated.Results Patients with T2DM showed decreased Z value around the right anterior cingulated cortex and the right medial pre-frontal cortex(cluster=121,t=-3.81,P＜ 0.05).There was no significant difference in grey matter volume between the two groups,and no correlation between Z value or duration and grey matter volume was found.Conclusions It suggests the abnormality of connectivity of default-mode network may precede the abnormality of grey matter volume in type 2 diabetes mellitus patients.The DMN might be a new potential tool in monitoring the change of cognition in patients with type 2 diabetes mellitus.