Use of modified cornstarch therapy to extend fasting in glycogen storage disease types Ia and Ib.
BACKGROUND
Type I glycogen storage disease (GSD) is caused by a deficiency of glucose-6-phosphatase resulting in severe fasting hypoglycemia.


OBJECTIVE
We compared the efficacy of a new modified starch with the currently used cornstarch therapy in patients with type Ia and Ib GSD.


DESIGN
This was a randomized, 2-d, double-blinded, crossover pilot study comparing the commonly used uncooked cornstarch with the experimental starch in 12 subjects (6 GSDIa, 6 GSDIb) aged >or=13 y. At 2200, the subjects were given 100 g of digestible starch, and glucose and lactate were measured hourly until the subject's plasma glucose concentration reached 60 mg/dL or until the subject had fasted for 10 h. The order in which the products were tested was randomized in a blinded fashion.


RESULTS
The matched-pair Gehan rank test for censored survival was used to compare the therapies. The experimental starch maintained blood glucose concentrations significantly longer than did the traditional therapy (P = 0.013) in the 2-sided analysis. Most of the benefit was found to be after glucose concentrations fell below 70 mg/dL. The currently used cornstarch resulted in higher peak glucose concentrations and a more rapid rate of fall than did the new starch.


CONCLUSIONS
The experimental starch was superior to standard therapy in preventing hypoglycemia (<or=60 mg/dL). This therapy may allow patients with GSD to sleep through the night without awakening for therapy while enhancing safety. Additional studies are warranted to determine whether alternative dosing will further improve control in the therapeutic blood glucose range.