How does low blood sugar affect the body?

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People need sugar in their blood to help provide their cells with energy.

Hypoglycemia, otherwise known as low blood sugar levels, is when the concentration of sugar in the blood goes below the normal range. This can interfere with the body’s normal functioning.

Healthcare professionals typically measure blood sugar in milligrams per deciliter (mg/dl). In the general population, healthy blood sugar levels range from 60 to 140 mg/dl.

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) note that people with diabetes should aim for blood sugar levels of 80–130 mg/dl right before a meal. At 2 hours after the beginning of the meal, the blood sugar level should be below 180 mg/dl.

Mild-to-moderate symptoms of hypoglycemia include:

• confusion
• difficulty concentrating
• restlessness
• anxiety
• headaches
• cold sweats
• shivering
• racing pulse

In more severe cases, a person may have seizures, become unconscious, or be unable to eat or drink.

Some people experience several symptoms at once when blood sugar levels drop, whereas others only experience one or two.

The NIDDK note that on a short-term basis, a person may experience low blood sugar if they have increased their physical activity levels beyond their usual routine, skipped a meal, consumed alcohol without food, or vomited.

Sugar levels may also drop if the person does not consume enough carbohydrates.

In most cases, blood sugar levels drop too low because of treatment for diabetes — for example, if a person has taken too much insulin. Sometimes, the body naturally produces too much insulin, which can also lead to blood sugar levels dropping.

Medications for other conditions may also lower blood sugar levels as a side effect.

Alternatively, low blood sugar can occur due to liver conditions, such as hepatitis, or kidney problems.

If a person does not address low blood sugar, and the effects become more extreme, the condition can lead to several short- and long-term effects.

Short-term effects

In severe cases of low blood sugar, short-term complications can include:

• brain bleed
• heart attack
• impairment to a person’s cognitive function

Long-term effects

Low blood sugar levels have few direct links to critical long-term effects, but they can increase a person’s vulnerability to other conditions, such as heart disease.

For example, an older study found that participants with low blood sugar due to type 2 diabetes had an increased risk of developing heart-related conditions and problems in the blood vessels.

Hypoglycemia can also increase the risk of other conditions, including:

• eye disease
• kidney disease
• nerve damage

In severe cases, nerve cells can die from the lack of glucose supply. If there is damage to the nerves controlling the internal organs, the body can enter autonomic neuropathy.

A person with this condition loses the ability to detect low blood sugar levels, and they may not experience symptoms. They might not know that they have low blood sugar, preventing early intervention. This increases the risk of a person developing severe hypoglycemia.

Hypoglycemia can affect several body systems in different ways.

Digestive system

Extremely high or low levels of blood sugar can cause a condition called gastroparesis. Low blood sugar levels affect the signaling of the vagus nerve, which normally stimulates the stomach to empty.

Gastroparesis causes problems with the digestive system because it can cause food to spend too much time in the stomach before entering the small intestine. Short-term symptoms of the condition include stomach pain, nausea, and vomiting.

Endocrine and circulatory systems

Severely low blood sugar can also affect the endocrine and circulatory systems by damaging nerves that relay important information.

Effects on the endocrine system largely come from the neuroendocrine network, which controls how the body responds to low blood sugar levels.

The circulatory system responds to low blood sugar by reducing the amount of insulin it circulates.

Central nervous system

The central nervous system (CNS) includes the brain and spinal cord. Blood sugar is its primary source of energy, so it needs blood sugar to be above a certain level.

Due to this, the CNS responds quickly to a severe drop in blood sugar, activating different counterregulatory measures until the person’s glucose levels restore.

A person who is experiencing an episode of low blood sugar can treat themselves immediately by consuming foods or drinks that will quickly raise blood sugar levels.

Options include a glass of milk or orange juice and carbohydrate-rich foods, such as a sandwich.

If 15 minutes have passed and the symptoms have not changed, a person should eat or drink some more.

In cases of extremely low blood sugar levels, a person can become drowsy and confused, and they may lose consciousness. If this is a recurring event, a person may be able to treat their hypoglycemia with a glucagon injection.

However, if a glucagon injection is ineffective or not accessible, it is essential to call for emergency medical help immediately. The symptoms could become more serious, leading to seizures or a coma.

It is important to contact a doctor if a person:

• experiences symptoms of low blood sugar even after they consume food or a sugary drink
• has severe symptoms — for instance, losing consciousness
• has frequent episodes of low blood sugar

Consistently low blood sugar levels can be dangerous because a disrupted glucose supply can impair brain function. In severe circumstances, this can cause coma or death.

Anyone with concerns about their blood sugar levels should speak with a doctor.

If the cause of low blood sugar is temporary — such as when a person has missed a meal — obtaining glucose through food and a sugary drink should start recovery almost immediately.

However, hypoglycemia is not always treatable with food and drink. If a person often experiences low blood sugar or is likely to develop severe hypoglycemia, a doctor can provide a glucagon emergency kit, which includes an injection in case it is necessary.

For these individuals, wearing a medical alert bracelet can be a good idea so that others know what to do if a situation arises.

Low blood sugar, also called hypoglycemia, can be a temporary condition that arises if a person does not eat for a while or exercises more intensely than usual.

It causes mild-to-moderate symptoms that include dizziness, hunger, and weakness, and a person can treat it quickly by consuming sugary foods or drinks.

Certain conditions, such as diabetes, can also cause low blood sugar. In cases such as these, the symptoms can be more frequent and intense. Severe hypoglycemia can have extreme consequences.

If a person has fainted, is having seizures, or is unable to eat or drink, bystanders can check whether they are wearing a medical alert bracelet or carrying a glucagon injection kit and call for an ambulance.