May hydrolyze glucose-6-phosphate to glucose in the endoplasmic reticulum. May be responsible for glucose production through glycogenolysis and gluconeogenesis (By similarity). D-glucose 6-phosphate + H2O = D-glucose + phosphate Carbohydrate biosynthesis; gluconeogenesis. Specifically expressed in pancreas and also detected to a lower extent in testis. Expressed by most islet cells in the pancreas (at protein level). N-glycosylated; the non-glycosylated form is more unstable and is degraded through the proteasome. Genetic variations in G6PC2 define the fasting plasma glucose levels quantitative trait locus 1 (FGQTL1) [MIM:612108]. The normal fasting plasma glucose level in the plasma is defined as less than 100 mg per deciliter (5.55 mmol per liter). Higher fasting plasma glucose levels predict type 2 diabetes in young adults and increases the risk of mortality. Belongs to the glucose-6-phosphatase family.