These 4 patients developed DKA despite receiving <10 ng/mL of TAC, indicating appropriate trough levels for minimizing diabetes risk.[13] TAC effect on insulin secretion is considered dose- and time-dependent in vitro.[9] The maximal decrease in insulin secretion is seen after 72 hours, and no further decrease occurred.[9] According to that data, we assumed that insulin secretion ability was suppressed several days after TAC administration. Here, INS is linked to diabetes mellitus.