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Fructose has often been suggested as a treatment for hypoglycemia. It does contribute toward formation of Glucose and glycogen synthesis. The mechanism of glucose production is as follows- 

Increased concentrations of Dihroxy acetone phosphate (DAP) and glyceraldehyde 3-phosphate (GAP) produced from the metabolism of fructose in the liver drive the pathway toward glucose and subsequent glycogen synthesis. (See figure)

Dihydroxyacetone phosphate and glyceraldehyde -3-P produced from fructose
metabolism condense together in the presence of Aldolase to form Fructose 1,6 bisphosphate, that is cleaved by fructose 1,6 bisphosphatase to form fructose-6-P. Glucose-6-P produced from Fructose-6-P by the action of Phospho hexose isomerase is converted to free glucose by the action of glucose-6-phosphatase. Hence by these reactions, Glucose is produced from fructose, blood glucose level rises. Surplus glucose-6-P can enter pentose phosphate pathway or can be converted to Glucose-1-P under the effect of Phosphoglucomutase and can be used up for the formation of Glycogen.

There are several good reasons to discourage the use of fructose to treat hypoglycemia

1) The process of formation of glucose from fructose is not an immediate process.
2) Secondly the conversion of fructose to glucose uses 2 ATPs. One ATP is spent at the first step for the formation of fructose-1-P and the second ATP is spent for the conversion of glyceraldehyde to Glyceraldehyde-3-P (Figure ).Normal hepatic activity alone utilizes all of the liver’s ATP-synthesizing capacity.  There is no good reason to increase hepatic ATP utilization for fructose metabolism. Glucose metabolism on the other hand produces ATP instead of utilizing.
3)   Moreover fructose is not a direct energy source for brain and muscle as these tissue lack fructokinase and fructose transporters while Glucose is a preferred fuel for brain and can be utilized in almost all the cells of the body. Hence Glucose (also called dextrose) instead of fructose can be given orally or intravenously depending upon the situation to treat hypoglycemia.

Figure-showing the inter relationship of fructose and glucose metabolism
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