Glymphatic function and its influencing factors in different glucose metabolism states

Figure 1 Schematic illustration of the diffusion tensor image analysis method along the perivascular space. A: Schematic diagram showing the relationship between the direction of the perivascular space (gray cylinder) and the direction of the projection fibers (blue) and association fibers (green). Note that the orientation of the perivascular space is perpendicular to the projection and association fibers; B: Diffusion tensor image superimposed color shows the distribution of projection fibers (z-axis: Blue) and association fibers (y-axis: Green). Four regions of interest were placed on both sides of the projection fibers (projection region) and the association fibers (association region) to measure the diffusion coefficients in the three directions (x, y, and z axes).

Figure 2 The left-side\right-side\mean diffusion tensor image analysis method along the perivascular space index was evaluated. A: The diffusion tensor image analysis method along the perivascular space (DTI-ALPS) index of the left-side cerebral hemisphere in patients with type 2 diabetes mellitus (T2DM) was significantly lower than in the normal glucose metabolism (NGM) group; B: The DTI-ALPS index of the right cerebral hemisphere in patients with T2DM was significantly lower than that in the prediabetes group and the NGM group; C: The mean DTI-ALPS index of both cerebral hemispheres in patients with T2DM was significantly higher in the prediabetes and NGM groups. T2DM: Type 2 diabetes mellitus; NGM: Normal glucose metabolism; DTI-ALPS: Diffusion tensor image analysis method along the perivascular space; L-DTI-ALPS: Diffusion tensor image analysis method along the perivascular space index of the left cerebral hemisphere in prediabetes and type 2 diabetes mellitus; R-DTI-ALPS: Diffusion tensor image analysis method along the perivascular space index of the right cerebral hemisphere of prediabetes and type 2 diabetes mellitus; Mean-DTI-ALPS: Mean Diffusion tensor image analysis method along the perivascular space index in both cerebral hemispheres.

Figure 3 The mini-mental state examination score in the type 2 diabetes mellitus group was significantly lower than that in the normal glucose metabolism and prediabetic groups. T2DM: Type 2 diabetes mellitus; NGM: Normal glucose metabolism; MMSE: The mini-mental state examination.

Figure 4 The correlation between the diffusion tensor image analysis method along the perivascular space index and other clinical features. A: The left-side diffusion tensor image analysis method along the perivascular space (DTI-ALPS) index in the prediabetes group was positively correlated with 2-hour postprandial glucose (2hPG) (r = 0. 582, P = 0.009, 95%CI: 0.192 to 0.830); B and C:The left-side DTI-ALPS index in the prediabetes group was negatively correlated with total cholesterol (r = -0.567, P = 0.011, 95%CI: -0.831 to -0.152) and low-density lipoprotein (r = -0.545, P = 0.016, 95%CI: -0.720 to 0.235); D and E: The right-side DTI-ALPS index in the prediabetes group was negatively correlated with waist-to-hip ratio (r = -0. 495, P = 0.031, 95%CI: -0.784 to 0.017) and glycosylated hemoglobin (HbA1c) (r = -0.662, P = 0.002, 95%CI: -0.867 to -0.122); F and G: The mean DTI-ALPS index in the prediabetes group negatively correlated with waist-to-hip ratio (r = -0.467, P = 0.044, 95%CI: -0.770 to 0.067) and HbA1c (r = -0.725, P = 0.0004, 95%CI: -0.886 to -0.398); H:The mean DTI-ALPS index in the prediabetes group was positively correlated with 2hPG (r = 0.477, P = 0.039, 95%CI: -0.103 to 0.797); I: The left-side DTI-ALPS index in the type 2 diabetes mellitus (T2DM) group was positively correlated with height (r = 0.553, P = 0.009, 95%CI: -0.142 to 0.822); J: The left-side DTI-ALPS index in the T2DM group was negatively correlated with high-density lipoprotein (HDL) (r = -0.548, P = 0.010, 95%CI: -0.792 to -0.109); K: The right-side DTI-ALPS index in the T2DM group was positively correlated with height (r = 0.621, P = 0.003, 95%CI: 0.096 to 0.828); L: The mean DTI-ALPS index of the T2DM group was positively correlated with height (r = 0.651, P = 0.001, 95%CI: 0.016 to 0.853); M: The mean DTI-ALPS index in the T2DM group negatively correlated with HDL (r = -0.544, P = 0.010, 95%CI: -0.802 to -0.013). T2DM: Type 2 diabetes mellitus; NGM: Normal glucose metabolism; DTI-ALPS: Diffusion tensor image analysis method along the perivascular space; L-DTI-ALPS: Diffusion tensor image analysis method along the perivascular space index of the left cerebral hemisphere in prediabetes and type 2 diabetes mellitus; R-DTI-ALPS: Diffusion tensor image analysis method along the perivascular space index of the right cerebral hemisphere of prediabetes and type 2 diabetes mellitus; Mean-DTI-ALPS: Mean Diffusion tensor image analysis method along the perivascular space index in both cerebral hemispheres; 2hPG: 2-hour postprandial glucose; TC: Total cholesterol; LDL: Low-density lipoprotein; HbA1c: Glycosylated hemoglobin; HDL: High-density lipoprotein.