P-240: Case report:when hypoglycemia meets autoimmunity: a challenging intersection of glycogen storage disease type ix and type 1 diabetes in early childhood
A AlshahranyAbstract
Introduction
GSD IX is a hepatic glycogenolysis defect causing hypoglycemia and hepatomegaly, whereas T1DM causes insulin deficiency and hyperglycemia. Their coexistence creates a rare metabolic paradox.
Objectives
To describe the clinical course and management challenges of combined GSD IX and T1DM.
Methods
A 4-year-old girl with PHKG2-related GSD IX was followed longitudinally.
Results
She presented with hepatomegaly and elevated transaminases. Genetic testing confirmed GSD IX by identifying a homozygous likely pathogenic variant in the PHKG2 gene, consistent with hepatic phosphorylase kinase deficiency and impaired glycogenolysis. This variant affects enzyme activity involved in glycogen breakdown, explaining the patient’s predisposition to fasting hypoglycemia and hepatomegaly. During follow-up, she developed T1DM at age of 3 years, confirmed by positive GAD65 (185 IU/mL), IA-2 (72 IU/mL), low C-peptide (0.18 ng/mL), and insulin requirement.
Conclusions
This rare coexistence causes extreme glycemic variability. CGM-guided insulin and permissive hyperglycemia are essential, while glucagon is unreliable.