Blood sugar level In humans, glucose is the primary source of energy, and is critical for normal function, in a number of tissues, particularly the human brain which consumes approximately 60% of blood glucose in fasted, sedentary individuals. Glucose can be transported from the intestines or liver to other tissues in the body via the bloodstream. Cellular glucose uptake is primarily regulated by insulin, a hormone produced in the pancreas. Glucose levels are usually lowest in the morning, before the first meal of the day, and rise after meals for an hour or two by a few millimoles. Blood sugar levels outside the
Glycogen for internal use and is not shared with other cells. This is in contrast to liver cells, which, on demand, readily do break down their stored glycogen into glucose and send it through the blood stream as fuel for other organs. Glycogen was discovered by Claude Bernard. His experiments showed that the liver contained a substance that could give rise to reducing sugar by the action of a "ferment" in the liver. By 1857, he described the isolation of a substance he called ""la matière glycogène"", or "sugar-forming substance". Soon after the discovery of glycogen in the liver, A. Sanson