Glycogen storage disease type Ia (GSD Ia) is a rare autosomal recessive disorder caused by a deficiency in glucose 6-phosphatase-α (G6PC). Patients primarily suffer from failure to thrive, hepatomegaly and severe fasting intolerance, biochemically characterized by hypoketotic and hyperlipidemia. Since they display clinical heterogeneity in biochemical symptoms and long-term hepatic complications, preclinical exploration of pathophysiological mechanisms and biomarkers is imperative for better prognosis and monitoring. To achieve this, an untargeted proteomics workflow was employed for identifying protein changes in liver and plasma from liver-specific G6pc knockout GSD Ia mice under fed and fasted conditions. Providing a link between the disease effects of GSD Ia in the liver and how these liver-specific effects present in the circulation under controlled (fed) and metabolic dysregulation (fasted) conditions. In liver proteomics results, protein levels related to the metabolism of glucose and lipids were up-regulated in GSD Ia mice versus controls. Differences were also observed in the proteasome, ribosome, NAD+ metabolism, hepatocellular detoxification, and synthesis of genotoxicity substances.. In plasma proteomics, proteins associated with complement and coagulation cascades decreased in GSD Ia.. The differences in both the liver and plasma were in general more pronounced in fasted GSD Ia mice. The overlapping differentially regulated plasma and liver proteins were subsequently identified for their potential as plasma biomarkers of hepatic complications, namely early-stage liver failure (SERPINA1E, C8b, and MBL2) non-alcoholic fatty liver disease (GPI1, UGP2, ALDOB, ACLY and FASN) and early hepatocellular carcinoma (PSMA4, PSMA7, PSMB5, and SDHA).