Continuous glucose monitoring in children with glycogenosis

Rationale: Glycogen storage diseases (GSD, glycogenosis) are a group of hereditary disorders of carbohydrate metabolism that is characterized by excess glycogen accumulation in various organs and tissues due to deficiency or absence of glycogen-splitting enzymes. GSD diagnostics requires an assessment of the patient's health status, severity and frequency of hypoglycemias, as well as the choice of a strategy for nutritional support to prevent hypoglycemia.

Aim: To assess efficacy of continuous glucose monitoring (CGM) as a  new method to diagnose hypoglycemia in children with hepatic types of GSD and the role of this assessment method in personalization of nutritional regimen in these disorders.

Materials and methods: The study included 51 child with confirmed diagnosis of GSD at the age of 6.9 ± 0.7  years, of them 36  boys and 15  girls. Thirty three percent of patients had GSD type I, 22% – type III, 45% – types VI and IX. All patients had their glycemic levels measured as glycemic profiles and oral glucose tolerance test (OGTT), as well as by means of real-time CGM. The results were analyzed both in the whole group of patients and in the groups with various GSD types.

Results: Measurement of glycemic profiles in children with GSD at daytime did not detect any significant abnormalities. During OGTT, more rapid decline of glucose levels was seen in younger kids and in patients with GSD type I; however, the differences were not statistically significant (11  patients (65%  of cases) had the lowest glucose levels at 180  minutes of the test: 3.1 ± 0.3 mmol/L, p > 0.05). Fasting hypoglycemia in the OGTT was found in 4  (24%) children with GSD type I  and in 3  (13%) children with GSD types VI and IX. Hypoglycemia at the end of the test was seen in 13 (76%) patients with GSD type I, in 3 (27%) with type III, and in 12 (55%) with types VI and IX. CGM showed hyperglycemia (10.2 ± 0.3 mmol/L) for 1 to 1.5 hours after a meal. Hypoglycemic episodes were registered at night time in 48 (94.1%) of children indicating the need for additional night feeding. Maximal total duration of low glucose levels was found in type  I  of the disease (10.2 ± 2.4  hours). Analysis of CGM results depending on GSD type showed that despite comparable glucose levels, more significant abnormalities are found in GSD type I (the proportion of hyperglycemic periods was 10.2 ± 2.3%, their duration 6.9 ± 1.8  hours; the proportion of hypoglycemic periods was 13.5 ± 2.6%, their duration 10.2 ± 2.4 hours, p < 0.05).

Conclusion: The results obtained indicate the necessity to use CGM in all GSD patients to diagnose and prevent hypoglycemia that would be the basis to elaborate individual nutritional recommendations.