Glucose uptake of hepatocytes and pancreatic beta cells (in mice, but GLUT1 in human beta cells; see Reference 1). The high Km of GLUT2 allows for glucose sensing; rate of glucose entry is proportional to blood glucose levels. GLUT4 transporters are insulin sensitive, and are found in muscle and adipose tissue. As muscle is a principal storage site for glucose and adipose tissue for triglyceride (into which glucose can be converted for storage), GLUT4 is important in post-prandial uptake of excess glucose from the bloodstream. Moreover, several recent papers show that GLUT 4 is present in the brain also. The drug metformin
Blood sugar level Blood sugar level The blood sugar level, blood sugar concentration, or blood glucose level is the amount of glucose present in the blood of humans and other animals. Glucose is a simple sugar and approximately 4 grams of glucose are present in the blood of a human at all times. The body tightly regulates blood glucose levels as a part of metabolic homeostasis. Glucose is stored in skeletal muscle and liver cells in the form of glycogen; in fasted individuals, blood glucose is maintained at a constant level at the expense of glycogen stores in the liver and skeletal muscle.