The parameter k4 is the rate constant for glucose uptake facilitated by insulin and glucose (Fig 1A), which conceptually corresponds to insulin sensitivity, and the result that k4 for NGT subjects was significantly higher than that for IGT or T2DM groups is consistent with the finding that both simulated and actual ISI for IGT or T2DM groups was lower than that for NGT (Fig 1C and 1D). Here, INS is linked to type 2 diabetes mellitus.