INS and type 1 diabetes mellitus: Managing postprandial glucose in Type 1 Diabetes Mellitus (T1DM) requires understanding how carbohydrate intake affects glucose through both direct pathways and insulin-mediated compensation.<sup>1,2</sup> Standard analyses often treat insulin as a confounder rather than a mediator, obscuring the distinct roles of these two causal channels and hiding clinically important heterogeneity in how different patients respond to carbohydrate intake.