He can burn the glucose for the energy immediately if the levels of glucose in the blood are not in a stable level of 20 g of glucose in the circulating blood supported for hour.
It will not be necessary to him for the energy immediately, then he is converted in glycogenic in the liver or muscles.

The liver has the capacity to store 100 grasses of glycogen. The muscles have the capacity to store between 250-400 grasses of glycogen, depending on the muscular mass and physical condition. Hepatic glycogen supply of energy for the whole body.

Muscular glycogen you punish fountains of energy for the muscles.
If the body has an excess of glucose, and all the stocks of glycogen are full, the excess glucose is converted in fat by the liver and stored like adipose cloth (physical fat) around the body.

Necessary, it can be burnt the oily acids like fuel (but the fat cannot be converted again in glucose).