Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Follow the personal emergency plan whenever food or cornstarch cannot be kept down.
Seek emergency help for:
Use the person’s specialist emergency instructions and tell emergency staff that intravenous glucose may be needed.
Vomiting or diarrhoea can become urgent quickly because the body cannot rely on stored glycogen in the usual way.
Contact the metabolic team promptly for repeated low readings, a change in usual fasting tolerance, persistent vomiting, or problems with feeding equipment.
People with GSD Ib should seek prompt advice for fever, spreading skin redness, worsening mouth sores, severe abdominal pain, or bloody diarrhoea because neutropenia can make infections more significant.
Routine appointments are the right place to discuss growth, puberty, diet, exercise, medication effects, or gradual changes in liver or kidney tests.
The article also says
Do not give food or drink to someone who is unconscious or unable to swallow safely.
Standard glucagon rescue may not work normally in GSD I because the liver cannot complete glucose release.
Every sign above is quoted from the sofidex article on von gierke disease. If you are not sure, err upward — it is always reasonable to be checked.