GFAP and type 2 diabetes mellitus: Therefore, in the current study, we measured plasma GFAP levels in T2D patients following the O-BN diet for 3 months and analyzed possible correlations with psychological well-being and the neurodegeneration marker neurofilament light polypeptide (NfL) in addition to peripheral metabolic (e.g., glucose, insulin) and inflammation (e.g., cytokines) markers, as well as markers for gut barrier leakage.