GCG and diabetes mellitus: Thus, to determine whether lack of glucagon signaling would also prevent hyperglycemia and diabetes in the context of a more severe insulin deficiency, we used a transgenic model of diphtheria toxin (DT)-mediated β-cell ablation, termed RIP-DTR, which leads to an almost complete β-cell elimination (Thorel et al., 2010; Chera et al., 2014).