GCGR and Hyperglycemia: Interestingly, ablation of the β-cells using high-dose streptozotocin, though causing severe hyperglycemia and hyperketonemia in the wildtype littermates, did not cause hyperglycemia or laboratory manifestations of diabetes in these knockout mice, indicating that ablating Gcgr prevents insulin-deficient type 1 diabetes in mice (Lee et al., 2011).