Endogenous Glucose Production in Patients With Glycogen Storage Disease Type Ia

Each subject will be administered two oral \[6,6-2H2\]glucose loads (pre-prandial, fed) in the hospital setting and one oral \[6,6-2H2\]glucose load at home setting (random time). Capillary blood samples will be collected on filter paper 10 times at specific time points after each oral \[6,6-2H2\]glucose load.