Dynamic changes in the sphingolipid metabolic profile during progression from a healthy condition to Pre-DM, and then to T2DM. Glucosyl ceramide, #P<0.01, T2DM vs. Pre-DM and *P<0.05, T2DM vs. Controls; sphingosine-1 phosphate, $P<0.001, Controls vs. T2DM and #P<0.01, Controls vs. Pre-DM; sphinganine, #P<0.01, Controls vs. T2DM, and $P<0.001, Controls vs. Pre-DM; sphingomyelin, #P<0.01, Controls vs. T2DM; and Sphingosine, *P<0.05, Controls vs. T2DM. DM, diabetes mellitus; T2DM, type 2 DM.