GCG and diabetes mellitus: Glucagon levels can vary from normal (usually <200 pg/mL) to as high as 14,300 pg/mL, and 66% to 81% patients have diabetes at the time of diagnosis.2,9 In accordance with this, in our cohort, glucagon levels varied from 245.6 pg/mL to 1570 pg/mL and 83% (5/6) patients had diabetes at the time of diagnosis.