The goal of this study is to determine if the Lactate Plus meter is accurate compared to lab lactate levels, and to determine if the Accu chek guide glucometer is accurate compared to lab serum glucose levels in patients with Glycogen Storage Disease Types Ia, Ib and XI.

To determine this, patient's will have a one-time planned admission to Connecticut Children's for approximately 8 hours and receive hourly blood draws as well as finger-sticks.

Inclusion Criteria:

1. Patients with diagnosed/confirmed (by liver biopsy or genetic testing) Glycogen Storage Disease Type Ia/Ib (ICD 10 code: E74.01) or XI (74.09).
2. For pediatric participants: Ability of child's parent/legal guardian to understand and the willingness to sign a written informed consent document
3. For adolescents: assent to participate
4. For adults: Ability to understand and the willingness to sign a written informed consent

Exclusion Criteria:

1. Patients with Glycogen storage disease unspecified
2. Patients not meeting inclusion criteria
3. Patients unable to provide consent
4. Patients who decline to be in the study

Patients birth to age 60 years with diagnosed Glycogen Storage Disease Type Ia/Ib or XI.