Diabetes mellitus one group, whereas type 2 encompasses four categories. This is hoped to improve diabetes treatment by tailoring it more specifically to the subgroups. Insulin is the principal hormone that regulates the uptake of glucose from the blood into most cells of the body, especially liver, adipose tissue and muscle, except smooth muscle, in which insulin acts via the IGF-1. Therefore, deficiency of insulin or the insensitivity of its receptors play a central role in all forms of diabetes mellitus. The body obtains glucose from three main sources: the intestinal absorption of food; the breakdown of glycogen (glycogenolysis), the storage form
Glucose 6-phosphate an allosteric activator of glycogen synthase, which makes sense because when the level of glucose is high the body should store the excess glucose as glycogen. On the other hand, glycogen synthase is inhibited when it is phosphorylated by protein kinase during times of high stress or low levels of blood glucose, via hormone induction by glucagon or adrenaline. When the body needs glucose for energy, glycogen phosphorylase, with the help of an orthophosphate, can cleave away a molecule from the glycogen chain. The cleaved molecule is in the form of glucose-1-phosphate, which can be converted into G6P by phosphoglucomutase.