Hydrolyzes glucose-6-phosphate to glucose in the endoplasmic reticulum. May form with the glucose-6-phosphate transporter (SLC37A4/G6PT) a ubiquitously expressed complex responsible for glucose production through glycogenolysis and gluconeogenesis. Probably required for normal neutrophil function (By similarity). D-glucose 6-phosphate + H2O = D-glucose + phosphate Inhibited by vanadate. Carbohydrate biosynthesis; gluconeogenesis. Expressed in liver and kidney. It is the major glucose-6-phosphatase expressed in the small intestine. Up-regulated upon fasting. Belongs to the glucose-6-phosphatase family.