Fructose-1,6-bisphosphatase deficiency is an inherited metabolic disorder in which the body cannot properly make glucose. Glucose is the main type of sugar in the blood and a primary source of energy for the body's cells. Fructose-1,6-bisphosphatase deficiency is inherited in an autosomal recessive manner. Inherited genetic changes in the FBP1 gene cause a deficiency of the enzyme fructose-1,6-bisphosphatase. This deficiency, in turn, results in impaired production of glucose.