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.
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?
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.
- 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.
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.
People may experience hypoglycemia for other reasons.
- Some medications: Quinine, a drug used for malaria, can trigger hypoglycemia. High doses of salicylates, used to treat rheumatic disease, or propranolol for hypertension (high blood pressure) may also cause blood sugar levels to drop. It can also happen when a person takes diabetes medication without having diabetes.
- Alcohol abuse: Drinking large amounts of alcohol can cause the liver to stop releasing stored glucose into the bloodstream.
- Some liver diseases: Drug-induced hepatitis can cause hypoglycemia.
- Kidney disorders: People with kidney disorders may have problems excreting medications, resulting in low blood sugar levels.
- Not eating enough: People with eating disorders, such as anorexia nervosa, may find that their blood sugar levels drop dramatically.
- Insulinoma: A tumor in the pancreas can cause the pancreas to produce too much insulin.
- Increased activity: Increasing levels of physical activity can lower blood sugar levels for some time.
- Endocrine problems: Some disorders of the adrenal and pituitary glands can lead to hypoglycemia. This is more likely to affect children than adults.
- Reactive, or postprandial, hypoglycemia: The pancreas produces too much insulin after a meal.
- Tumors: Tumors in parts of the body other than the pancreas can cause hypoglycemia. This is very rare.
- Severe illness: During times of critical illness, many different organs can be affected, including the pancreas. This can lead to hypoglycemia.
Measuring blood sugar levels can diagnose hypoglycemia.
Anybody who has a hypoglycemic attack, but does not know why, should see a doctor as soon as possible.
The doctor will probably order a blood test to measure blood sugar levels.
They will also ask about symptoms, and whether they improve after blood sugar levels return to normal.
The doctor will need to check the patient's medical history, whether they have been taking any medications, and about their alcohol consumption.
A collection of three criteria, known as Whipple's criteria, can suggest that symptoms stem from a pancreatic tumor.
The three criteria of Whipple's Triad are as follows:
- Signs and symptoms indicate hypoglycemia.
- When symptoms occur, a blood test shows low plasma glucose levels.
- When glucose is raised to normal levels, symptoms go away.
Some patients may not show signs and symptoms during their initial doctor's visit. If this happens, they may need to fast for a specified period, usually overnight. This allows hypoglycemia to occur so that a diagnosis can be made.
Some patients may have to be hospitalized and undergo a longer period of fasting. If the patient exhibits symptoms after having something to eat, blood sugar levels will need to be tested after eating.
There are two possible treatment approaches for hypoglycemia:
- Immediate treatment aims to resolve the abnormally low blood sugar attack.
- Treating the underlying cause can provide a long-term solution.
A patient with abnormally low blood sugar needs to eat or drink something with sugar as soon as possible to end the hypoglycemia attack.
For rapid results, they can consume a glucose tablet, sugar lump, candies, or a glass of fruit juice. This should be followed by slower-release carbohydrates, such as cereals, bread, rice, or fruit.
A person with diabetes should check their blood glucose and treat the hypoglycemia, then wait 15 to 20 minutes and check their blood sugar again.
If the blood glucose is still low, the process should be repeated. The person should eat some glucose, wait about 15 to 20 minutes, then check blood sugar again.
It is important for people with diabetes to stick to regular eating times - this is vital for keeping blood glucose levels as stable as possible.
If symptoms are severe, and the individual cannot treat themselves, somebody else will need to apply honey, treacle, jam, or Glucogel to the inside of the cheeks and then gently massage the outside of the cheeks.
They should start feeling better within 10 to 20 minutes.
If the patient loses consciousness, they should be placed into the recovery position, and a qualified health professional should administer a glucagon injection.
If this is not possible, the patient must be taken at once to the emergency department of a hospital.
If the patient has lost consciousness, food or drink should not be placed into the mouth, as it could block the airways.
A number of dietary factors may help control hypoglycemia.
High-protein diet: A low-sugar, high-protein diet has been recommended in the past for people with hypoglycemia, but this may reduce glucose tolerance worse and add unwanted fat to the diet.
Low-sugar diet: A low intake of simple sugars and a high intake of complex carbohydrates is recommended, as carbs that take a long time to absorb can help prevent glucose swings.
Small, frequent meals: Eating small meals, but more than three a day, can help maintain blood sugar levels.
Hypoglycemia and hyperglycemia
Hypoglycemia and hyperglycemia can both affect people with diabetes.
A person with hypoglycemia has too little glucose in their blood, but a person with hyperglycemia has too much.
Hypoglycemia is when blood glucose levels are below 4 mmol/L (72mg/dL).
Hyperglycemia is when:
- fasting blood glucose levels are over 7.0 mmol/L (126 mg/dl), or
- two hours after eating, blood glucose levels are over 11.0 mmol/L (200 mg/dl)
Ways of preventing hypoglycemia include:
- Checking blood glucose levels: Check blood sugar levels regularly and know how to identify the onset of symptoms.
- Eat regularly: Keep to an eating routine.
- Alcohol: Follow the daily alcohol limits recommended by a doctor, and eat something after having a drink.
- Exercise: Eat carbohydrate-rich food before exercising.
- Be ready: Carry a container of sugary fruit juice or a candy bar in case symptoms appear.
- Let people know : Those who are prone to low blood sugar should let friends, colleagues, and family members know.
- ID: People with diabetes should carry a form of ID or medical bracelet. This will enable healthcare providers, emergency services, and others to know what to do sooner.
A person with diabetes should follow their diabetes management plan carefully.
Those without diabetes who are prone to hypoglycemia should eat small quantities of food frequently throughout the day.