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
Alpha cell Alpha cell Alpha cells (more commonly alpha-cells or α-cells) are endocrine cells in the pancreatic islets of the pancreas. They make up to 20% of the human islet cells synthesizing and secreting the peptide hormone glucagon, which elevates the glucose levels in the blood. To elevate glucose levels, glucagon binds to receptors on hepatocytes (liver cells) and some other cells (e.g. kidney cells). This activates an enzyme, glycogen phosphorylase, inside the hepatocyte to hydrolyse glycogen to glucose. This process is called glycogenolysis. In rodents, alpha cells are located in the periphery of the islets, however in humans the islet architecture