Blood sugar level

The fluctuation of blood sugar (red) and the sugar-lowering hormone insulin (blue) in humans during the course of a day with three meals. One of the effects of a sugar-rich vs a starch-rich meal is highlighted.[1]

The blood sugar level, blood sugar concentration, blood glucose level, or glycemia is the measure of glucose concentrated in the blood. The body tightly regulates blood glucose levels as a part of metabolic homeostasis.[2]

For a 70 kg (154 lb) human, approximately four grams of dissolved glucose (also called "blood glucose") is maintained in the blood plasma at all times.[2] Glucose that is not circulating in the blood is stored in skeletal muscle and liver cells in the form of glycogen;[2] in fasting individuals, blood glucose is maintained at a constant level by releasing just enough glucose from these glycogen stores in the liver and skeletal muscle in order to maintain homeostasis.[2] Glucose can be transported from the intestines or liver to other tissues in the body via the bloodstream.[2] Cellular glucose uptake is primarily regulated by insulin, a hormone produced in the pancreas.[2] Once inside the cell, the glucose can now act as an energy source as it undergoes the process of glycolysis.

In humans, properly maintained glucose levels are necessary for normal function in a number of tissues, including the human brain, which consumes approximately 60% of blood glucose in fasting, sedentary individuals.[2] A persistent elevation in blood glucose leads to glucose toxicity, which contributes to cell dysfunction and the pathology grouped together as complications of diabetes.[2]

Glucose levels are usually lowest in the morning, before the first meal of the day, and rise after meals for an hour or two by a few millimoles per litre.

Abnormal persistently high glycemia is referred to as hyperglycemia; low levels are referred to as hypoglycemia. Diabetes mellitus is characterized by persistent hyperglycemia from a variety of causes, and it is the most prominent disease related to the failure of blood sugar regulation. Diabetes mellitus is also characterized by frequent episodes of low sugar, or hypoglycemia. There are different methods of testing and measuring blood sugar levels.

Drinking alcohol causes an initial surge in blood sugar and later tends to cause levels to fall. Also, certain drugs can increase or decrease glucose levels.[3]

  1. ^ Daly ME, Vale C, Walker M, Littlefield A, Alberti KG, Mathers JC (June 1998). "Acute effects on insulin sensitivity and diurnal metabolic profiles of a high-sucrose compared with a high-starch diet" (PDF). The American Journal of Clinical Nutrition. 67 (6): 1186–96. doi:10.1093/ajcn/67.6.1186. PMID 9625092.
  2. ^ a b c d e f g h Wasserman DH (January 2009). "Four grams of glucose". American Journal of Physiology. Endocrinology and Metabolism. 296 (1): E11–21. doi:10.1152/ajpendo.90563.2008. PMC 2636990. PMID 18840763.
  3. ^ Walker, Rosemary and Rodgers, Jill (2006) Type 2 Diabetes – Your Questions Answered. Dorling Kindersley. ISBN 1-74033-550-3.