Glucose is a form of sugar that comes from either the diet or is produced by the liver, and that circulates throughout the blood to all the body’s cells. After it enters the cells, it is converted to energy, with each gram of glucose producing about 4 calories of energy. Energy from glucose fuels the activity of every cell in the body, and particularly the brain, which uses more than 2/3 of circulating glucose. Because it is so important the body has several ways of keeping the levels of glucose in the blood at just the right level. These include insulin from the pancreas – that prevents glucose levels from rising above normal (called hyperglycemia), and a variety of hormones (such as cortisol, glucagon, adrenalin, and growth hormone) that prevent levels from falling below normal (called hypoglycemia).
This is important because both hyperglycemia and hypoglycemia can cause serious harm.
Hyperglycemia, in the short term, promotes increased urination in an attempt to clear the body of excess glucose. This can cause dehydration, increased thirst, impaired sleep, and general malaise. If severe, a potentially fatal condition called ketoacidosis or coma can also develop. In the long term, it might lead to organ damage and a wide variety of serious health outcomes. Insulin and a wide variety of oral and injectable drugs can normalize glucose levels.
Mild hypoglycemia can cause hunger, sweating, mood changes, and other nonspecific symptoms, whereas severe hypoglycemia can cause seizures, confusion, accidents, coma and even death. Oral glucose and other sugars, as well as inhaled or injected glucagon (in an emergency) can raise glucose levels.
The Bottom Line: Glucose is an important energy source for the human body. There are potential risks of experiencing low or high concentrations of glucose on a regular basis.
About the author
Hertzel Gerstein
Hertzel is an endocrinologist and professor at McMaster University who is in high demand as a speaker, advocate, and educator on diabetes-related topics. His research focuses on using large, international randomized trials to identify and test new ways of preventing type 2 diabetes, reducing serious health outcomes like strokes and death, and achieving type 2 diabetes remissions.
