AQP4 and type 2 diabetes mellitus: In addition, the dependency of glymphatic clearance and cerebrospinal fluid- interstitial fluid exchange on aquaporin-4 water channel in different neurological conditions is well known [13, 25–28], and the animal model of T2DM showed reducing trend in the aquaporin-4 expression with an increased disease severity of the condition, which indicate a similar mechanism may underlie glymphatic dysfunction in T2DM patients and suggest consideration of aquaporin-4 water channel is crucial for assessment of the glymphatic system status.