What Is the Normal Blood Sugar Level?

Updated March 23, 2017

Blood sugar, also known as blood glucose, is vital for the body. Too much or too little blood sugar can have serious health risks, particularly if it occurs frequently over a long period of time.

How It Works

Foods that contain sugar or carbohydrates provide the body with blood sugar. The pancreas secretes a hormone called insulin in response to the blood sugar. Insulin bonds with the sugar, allowing it to become food for the brain and fuel for the body.

Normal Blood Sugar Levels

A normal blood sugar level ranges from 70 mg/dl to 120 mg/dl (milligrams of sugar to decilitres of blood). The level may rise or lower slightly in healthy people in reaction to a meal high in carbohydrates or strenuous exercise, but the spike is not severe or prolonged.

High Blood Sugar Levels

A blood sugar level higher than 120 mg/dl is called hyperglycaemia. Hyperglycaemia may be a symptom of an underlying medical condition such as impaired glucose tolerance (IGT) or diabetes. The American Diabetes Association estimates that 8 per cent of the United States population has some form of diabetes.

Low Blood Sugar Levels

A blood sugar level below 70 mg/dl is called hypoglycaemia. Prolonged or severe hypoglycaemia, particularly in children, can be a symptom of a condition such as hyperinsulinism.


Both hyperglycaemia and hypoglycaemia can cause short- and long-term health issues. Hyperglycaemia carries more severe long-term risks such as heart and kidney disease and damage to blood vessels. Hypoglycaemia risks are much more severe in the short-term. Severe hypoglycaemia can quickly cause unconsciousness, seizures, coma or death.


Blood sugar levels are tested with a glucose meter. Glucose meters read small samples of the blood and display the blood sugar level within a minute or two. They can be purchased at any drugstore or pharmaceutical supply.

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About the Author

After attending Fairfield University, Hannah Wickford spent more than 15 years in market research and marketing in the consumer packaged goods industry. In 2003 she decided to shift careers and now maintains three successful food-related blogs and writes online articles, website copy and newsletters for multiple clients.