Blood glucose homeostasis
Cells derive their energy from glucose, and it is vital that glucose levels be tightly regulated. Too much glucose is toxic to cells while too little glucose leads to starvation. Blood glucose levels can fluctuate for a number of reasons, such as digestion after a meal and production of insulin by the liver, both of which lead to increased glucose levels, or from the transport of sugar into the cells and the loss of glucose in the urine, which lower blood glucose levels. Glucose homeostasis relies on many different molecules, cell types and organs.