Glucose transport and pharmacological control of glucose metabolism.

Glucose is an energetic substrate that plays an essential role, especially in those tissues that are vital for the functioning of whole organism, such as the nervous system, red blood cells, and leukocytes. The key metabolic role of glucose derives from its ability to supply energy rapidly and, under certain conditions, even in the absence of oxygen. Both these properties make glucose unique as a metabolic substrate, even though it produces less energy per molecule than other substrates, and it can be stored (as glycogen) only in limited amounts. It is noteworthy that there is a hierarchy in glucose utilization in the body. In vital tissues, glucose uptake is not subject to hormonal regulation and depends exclusively on blood levels, whereas in other tissues, such as muscle and adipose tissues, glucose uptake is finely regulated by specific hormones. These characteristics may explain why there is a tight physiological control of blood glucose levels. This chapter discusses the mechanisms and pharmacology of glycemic control.