A 5-year-old girl from rural Maharashtra presents with recurrent episodes of severe hypoglycemia triggered by fasting or infection. Liver biopsy shows massive glycogen accumulation. Enzyme assay reveals deficiency of glucokinase (hexokinase IV). Her cousin has a similar presentation but develops acute hemolytic anemia, jaundice, and dark urine during infections. Which feature best distinguishes glucokinase deficiency from glucose-6-phosphatase deficiency?