Continuous glucose monitoring in children with glycogen storage disease type I

BACKGROUND/OBJECTIVES: Glycogen storage disease type I (GSD I) is an autosomal recessive metabolic disorder caused by defects in the glucose-6-phosphatase complex. Deficient activity in the glucose-6-phosphatase-alpha catalytic unit characterizes GSD Ia and defects in the glucose-6-phosphate transporter protein characterize GSD Ib. Type Ia involves the liver, kidney and intestine (and Ib also leukocytes), and the clinical manifestations are hepatomegaly, failure to thrive, severe fasting hypoglycemia within 3-4 h after a meal, hyperlactatemia, hyperuricemia and hyperlipidemia. The aim of the present study was to examine the safety and efficacy of a continuous subcutaneous glucose monitoring system to determine the magnitude and significance of hypoglycemia in GSD I and to evaluate the efficacy of the revised dietary treatment. SUBJECTS/METHODS: Sixteen children with GSD I were studied over a 72-h period. Continuous glucose monitoring (CGM) was repeated in all patients 3-6 months after the first monitoring to examine the effects of revised dietary instructions on glycemic control. RESULTS: All the patients completed the study without any major adverse events. Significant periods of asymptomatic hypoglycemia (below 4 mmol/l, 70 mg/dl) were noted. There was a close correlation between CGM sensor and capillary blood glucose values measured by a glucometer. CGM indicated a considerable reduction in duration of hypoglycemia, liver size and improvements in secondary metabolic derangements such as hyperlacticacidemia and hyperlipidemia. CONCLUSIONS: CGM could be applied in the clinical setting to help the physician to identify hypoglycemic events, and repeated CGM may serve as a safe and useful tool for the assessment of the long-term management of patients with GSD I.