Most people effect with GSD drink cornstarch mixed in water every 2 to 6 hours throughout a 24 hour period.  Drinking cornstarch is used as the preferred method for keeping blood glucose levels normal, above 75.  Cornstarch acts as the bodies stored energy source.  Since glycogen, unaffected peoples normal energy resource, can not be retrieved.  Unfortunately cornstarch has no nutritional value, and can cause gas and bloating.  So meals are required and scheduling meals is essential for good management. 

Cornstarch is easy to administer, relatively easy to obtain (in most countries), and creates a nice blood glucose curve over a predictable period of time.