Insulin is a hormone secreted by the beta cells of the Islets of Langerhans of the pancreas. It performs the following functions: 1. It is responsible for increasing the oxidation of glucose in the cells. 2. It increases the permeability of the cell membrane to glucose. 3. It causes the conversion of excess glucose to glycogen, which is stored in the liver.
The hormone which initiates the conversion of glycogen to glucose is glycogen.