[Recent knowledge of the function of glucose transport molecules in cell membranes, of the regulation of their composition and of modification of their activity and changes in concentration in diseases (diabetes mellitus, Tumors)].

In the outer membrane of animal cells there exist different isoforms of glucose-transporters (GluT), that contain pores for the facilitative intake of glucose. The content of the various forms of GluT in the different cells is influenced by the stage of development and by the plasma-concentration of glucose. In the regulation of the glucose-concentration in the plasma the content of the skeletal musculature and of the adipose tissue in GluT type 4 plays an important role: It is insulin-dependent. In diabetes mellitus the content of the outer membranes of the cells of the mentioned tissues in GluT 4 is - in dependence of the degree of the disturbance - more or less reduced. The binding of insulin to the receptor in the musculature and in adipose tissue stimulates the transport of GluT 4 from the interior of the cells to the outer membrane. Fasting causes an increase in the content of GluT 4 in the musculature and a decrease in the adipose tissue. Tumor-cells have an increased uptake of glucose with the help of GluT.