Abstract Glycogen storage disease type 1a (GSD1a) is an autosomal recessively inherited inborn error of metabolism caused by a mutation in the G6PC gene, which encodes the catalytic subunit of glucose-6-phosphatase-α (G6Pase-α) enzyme. This enzyme plays a role in the final step of gluconeogenesis and glycogenolysis. Patients carrying GSD1a show growth retardation, hypoglycemia, hepatomegaly, hepatic steatosis, hyperlipidemia, hyperuricemia and lactic acidemia. Long-term symptoms include gouty arthritis and uric acid stones, osteoporosis, renal failure, intestinal impairment, cirrhosis and hepatic adenomas, and eventually, hepatocellular carcinoma. Hyperlipidemia is the indicator of poor metabolic control in GSD1a. Patients with variable levels of triglycerides (TGs) have been reported in the literature. We present a case of GSD1a that presented with severe hypertriglyceridemia (HTG) mimicking familial chylomicronemia syndrome.