Hypoglycemia (low blood sugar): Causes and treatment

Hypoglycemia refers to an abnormally low level of sugar, or glucose, in the blood. Hypoglycemia is not a disease in itself, it is a sign of a health problem.

The brain uses a lot of energy and needs glucose to function. Because the brain cannot store or manufacture glucose, it needs a continuous supply.

Signs of low blood sugar include hunger, trembling, heart racing, nausea, and sweating. Hypoglycemia is commonly linked with diabetes, but many other conditions can also cause low blood sugar.

This article will discuss the causes, diagnosis, and treatment of hypoglycemia, and the difference between hypoglycemia and hyperglycemia. We will also look at how to prevent it.

Fast facts on hypoglycemia

Here are some key points about hypoglycemia. More detail is in the main article.

Hypoglycemia is not a disease but a symptom of another condition.

Early symptoms include hunger, sweating, and trembling.

A common cause is diabetes.

Alcohol abuse and kidney disorders can also lower blood sugar levels.

What is hypoglycemia?

Woman feeling dizzy
Common symptoms of hypoglycemia include dizziness and tremors.

Hypoglycemia is a condition where there is not enough glucose, or sugar, in the blood.

Levels of blood sugar are below 4 mmol/L (72mg/dL).

Adults and children with mild hypoglycemia may experience the following early symptoms:


tremor or trembling




a pale face

heart palpitations

accelerated heart rate

tingling lips



Severe hypoglycemia is sometimes called diabetic shock.

It may involve:

concentration problems


irrational and disorderly behavior, similar to intoxication

inability to eat or drink


If a person does not take action when symptoms of hypoclycemia appear, it can lead to:


loss of consciousness


A person who regularly experiences hypoglycemia may become unaware that it is happening. They will not notice the warning signs, and this can lead to severe and possibly fatal complications.

Hypoglycemia is often a sign of diabetes, or poorly managed diabetes. Ignoring the signs of hypoglycemia can enable diabetes to become more severe.

Hypoglycemia in children

Hypoglycemia can affect children as well as adults, especially if they have diabetes. It may happen after taking too much insulin, exercising strenuously for some time, or not eating enough.

In children without diabetes, recurrent hypoglycemia may result from:

ketotic hypoglycemia, especially between the ages of 1 and 5 years

some medications

a health condition that is present from birth, such as hyperpituitarism or hyperinsulinism

Ketotic hypoglycemia is a potentially life-threatening condition that involves hypoglycemia and high levels of ketones bodies. The cause is unknown.

Some people experience low blood sugar during the night.

Signs include:


crying out in the night

feeling tired or irritable when waking

sweating more than usual during the night

If a child shows signs of confusion, dizziness, headache, irritability, sudden mood changes, or clumsy or jerky movements, they should see a doctor as soon as possible.

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Hypoglycemia can occur for various reasons. It often happens when a person with diabetes takes too much insulin.

Blood sugar regulation

The digestive system breaks down carbohydrates from the food we eat into different types of sugar molecules, one of which is glucose, the body’s main source of energy.

Glucose enters the bloodstream after we eat. However, glucose needs insulin—a hormone produced and excreted by the pancreas—before it can enter a cell. In other words, a cell would starve of energy if there were no insulin around, regardless of how much glucose there was.

After eating, the pancreas automatically releases the right amount of insulin to move the glucose in our blood into the cells. This lowers the blood sugar level. Any extra glucose goes into the liver and muscles in the form of glycogen, or stored glucose.

Insulin is responsible for bringing excess blood sugar levels back to normal.

If glucose levels have dropped because an individual has not eaten for a while, the pancreas secretes glucagon—another hormone—which triggers the breakdown of stored glycogen into glucose. This is then released into the bloodstream, bringing glucose levels back up.

Hypoglycemia and diabetes

People with type 1 diabetes do not produce insulin, while those with type 2 diabetes have cells which do not respond properly to insulin. They are both susceptible to rising blood-glucose levels, meaning that cells do not get enough energy.

People with both types of diabetes usually need to take medication such as insulin or other drugs to bring their blood sugar levels down.

If a person with diabetes takes too much insulin, their blood sugar levels can drop too low. This is hypoglycemia.

A person who takes insulin may take a normal amount for that time of day, but they may have eaten less than usual, or done more exercise, so their insulin requirement for that moment is lower than usual.

In other words, taking too much insulin does not necessarily mean that the patient increased the dosage. It just means that the insulin taken in was more than the body needed at that moment.

This can also happen when taking other types of diabetes drugs that cause the body to release too much insulin from the pancreas.

Other causes

People may experience hypoglycemia for other reasons.

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