SMPD1 and type 2 diabetes mellitus: Third, sphingolipid metabolism plays a novel regulatory role: HIIT increased acid sphingomyelinase (ASM) activity in T2DM, and ASM activation correlated with p-PARKIN upregulation, HIIT may redirect ceramide metabolism to overcome insulin resistance and trigger mitophagy, unlike endurance training (Hendlinger et al., 2025).