What is the 72-hour fast test?

Pt is allowed to drink non-caloric drink and given IV hydration, glucose checked every 6 hours, if it goes below 55 at any time, get C-peptide, proinsulin, insulin, beta hydroxybuteric acid, and oral hypoglycemia screen. then after 72 hours, give glucagon, if hypoglycemia is caused by insulin, when given glucagon glucose should increase by >25 mg/dl In normal individual (they have asymptomatic hypoglycemia, hormonally mediated glucose regulation, gluconeogenesis 50% of glucose production after overnight fasting, and almost all glucose after 42 hours, any hypoglycemia would occur only if there is a defect in ability to maintain normoglycemia.