Continuous Glucose Monitoring in Glycogen Storage Diseases: A Systematic Review of Clinical Utility, Accuracy and Patient Outcomes.

BACKGROUND

Achieving euglycemia in Glycogen Storage Diseases (GSD) depends on strict dietary adherence; however, intermittent monitoring frequently fails to detect rapid hypoglycemic excursions. This systematic review evaluates the clinical utility, accuracy and psychosocial impact of Continuous Glucose Monitoring (CGM) across hepatic GSD subtypes.

METHODS

We searched PubMed, Embase, Scopus, Web of Science and Cochrane Library (inception to December 2025) following PRISMA 2020 guidelines. Eligible studies included randomized trials, cohorts and case series reporting CGM outcomes in hepatic GSD.

RESULTS

Thirty-one studies (N = 323) met inclusion criteria, predominantly GSD Ia, Ib and III. CGM consistently identified asymptomatic hypoglycemia, with adult cohorts spending up to 12% of time below range (< 70 mg/dL) despite normal spot checks. In interventional settings, CGM-guided dietary titration improved Time in Range (e.g., 72%-86% in gene therapy trials) and reduced serum triglycerides and liver size. However, sensor performance showed a positive bias in the hypoglycemic range, potentially masking severe neuroglycopenia. Psychosocially, while CGM improved sleep quality scores, it introduced 'alarm fatigue' from false-positive alerts.

CONCLUSION

Emerging evidence suggests that CGM may shift GSD management from reactive treatment to proactive stabilization. It offers superior sensitivity for detecting occult hypoglycemia and guiding therapy, though its utility is tempered by sensor inaccuracy at lower limits and the burden of constant surveillance. Future implementation requires subtype-specific interpretation and sensors optimized for the hypoglycemic range.