Glucose is major energy substrate. It is typically provides more than half of total energy requirements on atypical ‘western’ diet and is the only utilisable source of energy for some tissues, for example erythrocytes and in the short term, the central nervous system.
Some body cells can also use other energy sources, such as fatty acids,but the cells of the brain can only use glucose. Glucose is by far the most plentiful monosaccharide found in blood, and the term blood sugar usually refers to glucose. In adults, the normal blood sugar level measured after a fast of 8-12 hours is in the range of 70-110 mg/100 mL.
The liver is the key organ involved in regulating the blood sugar level. The liver responds to the increase in blood glucose that follows a meal by removing glucose from the bloodstream. After meals, pancreas secretes the hormone insulin into the blood. Insulin increases the permeability of cell membranes to glucose so more can enter them. Level of blood sugar starts dropping soon after it starts entering the cell.
In the liver and muscle cells, insulin activates enzymes to convert the glucose into the storage molecule glycogen.
Biology of glucose
