The aim of this mini‐review was to: (i) summarize the current knowledge on glucagon responses during hypoglycemia in normal physiology and type 1 diabetes, and (ii) review human in vivo studies investigating glucagon responses during various stressful conditions in individuals with type 1 diabetes compared with the physiological response in nondiabetic individuals. The gene discussed is GCG; the disease is type 1 diabetes mellitus.