GCG and type 1 diabetes mellitus: While these preliminary findings must be confirmed in larger samples of T2D islets, they support the conclusions that 1) suppression of SST secretion from islet δ-cells acts as a permissive signal for counterregulatory glucagon release, and 2) this permissive signal may be compromised in T1D and advanced T2D (Vergari et al., 2020).