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What is Hypoglycaemia?

Last updated on 20th April 2023

Hypoglycaemia is a condition where your blood sugar level, otherwise known as blood glucose level, is lower than normal. Glucose is your body’s main energy source. When you eat, your body breaks down carbohydrates from foods such as pasta, rice, bread, milk and fruit and vegetables.

Glucose, which is the main energy source for your body, with the help of insulin, enters the cells of most of your tissues. Extra glucose is stored in your liver and muscles, in the form of glycogen. The condition known as hypoglycaemia mainly affects people with diabetes, especially if you take insulin.

Diabetes is a condition that causes a person’s blood sugar level to become too high, and insulin, or in some cases other medication, is used to lower blood sugar levels. Sometimes this can cause a person’s blood sugar level to become too low. Other drugs and a variety of other conditions can also cause low blood glucose in people who do not have diabetes.

You can usually treat low glucose levels easily yourself at home and will not require medical assistance. Treatment involves quickly getting your blood sugars back to a safe level with sugary drinks, snacks or medication. Severe low blood glucose is defined as when your blood glucose level drops so low that you can’t treat it yourself, however, this is not usually common.

Woman with diabetes

What are the symptoms of hypoglycaemia?

Having a low blood sugar level can affect different people in different ways and a person’s symptoms can change over time.

Signs of a low blood sugar level can include:

  • Sweating.
  • Feeling tired.
  • Feeling hungry.
  • Dizziness.
  • Shaking/trembling.
  • Tingling or numb lips, tongue or cheek.
  • Fast or irregular heartbeat.
  • Turning pale.
  • Feeling irritable, tearful or anxious.

If your blood sugar level is not treated your symptoms may become worse. This can include things like:

  • Confusion or difficulty concentrating.
  • Blurred vision or visual disturbances.
  • Weakness.
  • Unusual behaviour, slurred speech or clumsiness.
  • Feeling sleepy.
  • Loss of consciousness.
  • Seizures or fits.

A low blood sugar level can also happen when you are sleeping. You may wake up with headaches, tiredness, sweating or crying out in your sleep or having nightmares. Although you may not wake up or have any symptoms, low blood glucose can interfere with your quality of sleep.

This may affect your mood, quality of life and ability to work. Having low blood glucose during sleep can make you less likely to notice and treat any symptoms.

Severe hypoglycaemia is dangerous and needs to be treated straight away. It can cause serious complications including passing out, coma or death. Hypoglycaemia can also contribute to falls, injuries, dizziness, and motor vehicle accidents, and can contribute to a risk of developing dementia in older adults.

Repeated episodes of low blood glucose levels can lead to:

  • High blood glucose levels if your worry or fear of having low blood sugar levels prevents you from taking the medicines that you need to manage your diabetes.
  • Hypoglycaemia unawareness, a condition which you don’t notice any symptoms of low blood sugar until your blood sugar level has dropped very low.
Having seizure after not treating blood sugar levels

What to do if you have symptoms?

If you have symptoms of hypoglycaemia you can usually treat these yourself by having a sugary drink or snack; you should then test your blood sugar level again after ten minutes. If your blood sugar level has not improved, have another sugary snack and test again after ten minutes.

If your blood sugar level has then improved, you may need to eat your main meal containing a slow release carbohydrate such as bread or pasta. You do not usually need to seek medical help if you start to feel better and you have only had a few episodes of having low blood glucose levels.

You should speak to your doctor or diabetes team if you have repeated episodes of low blood sugar levels or if you stop getting any symptoms when your blood sugar levels are low.

This is known as hypoglycaemia unawareness, when your body and brain no longer produce signs and symptoms that warn you of low blood glucose such as shakiness or an irregular heartbeat. When this happens your risk of developing severe life-threatening hypoglycaemia increases.

If you have symptoms of hypoglycaemia, you should seek medical help immediately if:

  • You do not have diabetes.
  • You do have diabetes but hypoglycaemia isn’t responding to treatment such as drinking juice, eating sweets or having glucose tablets.

Emergency medical help should be sought for someone who has diabetes or has a history of hypoglycaemia if they have symptoms of severe hypoglycaemia or if they lose consciousness.

You should see your GP if you think you have symptoms of hypoglycaemia; they can arrange for some simple tests to check if your blood sugar level is low and try to find out what is causing it.

Man who could have hypoglycaemia

What causes hypoglycaemia?

The condition is often associated with people who have diabetes. Type 1 diabetes causes the level of glucose in your blood to become too high. This happens as your body cannot produce enough insulin which controls blood glucose.

Daily injections of insulin will keep your blood glucose level under control. Hypoglycaemia happens when your blood glucose level is too low. Type 2 diabetes is more common and also is where the level of glucose in your blood is too high. It can cause symptoms, for example excessive thirst, tiredness and needing to urinate often.

The condition can increase your risk of developing other conditions with your heart, eyes and nerves. It is often linked to being overweight, inactive or having a family history of type 2 diabetes. Diabetes UK provide support, information, including an online learning zone, advice, a helpline and other resources if you are affected by diabetes or would like to learn more.

In people who have diabetes, the main cause of low glucose levels are:

  • The effects of the medication, especially taking too much insulin which lowers blood sugar levels.
  • Not eating enough carbohydrate foods such as bread, cereals, pasta, potatoes and fruit.
  • Skipping or delaying meals.
  • Drinking alcohol.
  • Intense exercise.

Hypoglycaemia in people without diabetes is much less common. Possible causes without diabetes can include:

  • Excessive alcohol use – Drinking to excess without eating can block your liver from releasing stored glucose into your bloodstream.
  • Medications – Taking someone else’s diabetes medication accidently can cause hypoglycaemia. Other medications can cause hypoglycaemia especially in people with liver failure or children.
  • Insulin overproduction – A rare tumour of the pancreas can cause you to produce too much insulin. Other tumours can cause too much production of insulin-like substances.
  • Some critical illnesses – Certain liver illnesses, for example severe hepatitis or cirrhosis, can cause hypoglycaemia. Kidney disorders which prevent your body from excreting mediations can affect glucose levels.
  • Some eating disorders can result in your body not having enough of the substances it needs to create glucose. For further information about how eating disorders affect lives please see our knowledge base.
  • Hormone deficiencies – Certain adrenal gland disorders can result in deficiency of hormones that regulate glucose production.

How is hypoglycaemia diagnosed?

Your healthcare professional will want to know whether you use insulin or another medication to lower your blood sugar level. If you do and you have symptoms of hypoglycaemia you can test your blood sugar level with a blood glucose meter.

If you don’t use any medication that is known to cause hypoglycaemia, your healthcare professional will want to discuss what your symptoms have been, what your blood glucose level is when you are having symptoms, and if your symptoms improve when your blood glucose level improves. Your healthcare professional will likely conduct a physical examination and ask about your medical history.

For fasting hypoglycaemia you may have your blood glucose level checked every few hours. For reactive hypoglycaemia you might have a test called a mixed-meal tolerance test (MMTT). For this test you will have a type of protein drink with fats and sugar in. The drink will raise your blood glucose, making your body produce more insulin.

Your blood glucose level will then be checked over the next few hours. Both of these tests determine whether your blood glucose level drops too low. Your doctor may also check your blood for your insulin level.

Excessive drinking can cause hypoglycaemia

Treatment for hypoglycaemia

Treatment includes quickly getting your blood sugar level back to normal either with high sugar food or drinks or with medications. High sugar food and drinks can include things like fizzy drinks, but not a diet variety, or fruit juice or a sweet, for example a few jelly babies. Glucose tablets and glucose gels are also available.

Eating foods that contain a slow-release carbohydrate can help in maintaining a steady blood sugar level. This includes food such as pasta, bread, biscuits or some cow’s milk. Your doctor or dietitian may want to put in place a diet plan.

An example of this may be:

  • Eating small meals throughout the day, every three or so hours.
  • Having a variety of foods including protein both of the meat and non-meat variety, high fibre food such as wholegrain bread, fruit and vegetables.
  • Limiting foods that are high in sugar.

Hypoglycaemia is considered to be severe if you need help from someone to recover. You may need a glucagon injection or intravenous glucose. People with diabetes who are treated with insulin should have a glucagon kit for emergencies.

Family and friends should know where to find the kit and how to use it in an emergency. If you are helping someone who is unconscious, you should not try to give them food or drink. If there is no glucagon kit available or you don’t know how to use it, then it is important to get emergency medical help.

You can follow these steps:

  • Place them into the recovery position. Do not put anything into their mouth so as to prevent them from choking.
  • Call 999 for an ambulance if an injection of glucagon is not available or you do not know how to use it or if the person has had alcohol.

First Aid for Life provide some practical tips for how to help someone who is experiencing hypoglycaemia.

Preventing reoccurring hypoglycaemia requires your doctor to identify the underlying condition and treat it.

Depending on the underlying cause, treatment may include:

  • Medications – If medication is the cause then your doctor will likely suggest changing or stopping your medication or adjusting the dose.
  • Tumour treatment – A tumour in your pancreas is treated by surgical removal of the tumour. In some cases partial removal of the pancreas is necessary.
Checking blood sugar levels often can help prevent other issues

Can hypoglycaemia be prevented?

If you have diabetes and are therefore taking insulin or other medicines that lower blood glucose, there are things you can do to help prevent low blood glucose levels:

  • Regularly check your blood glucose level. The most common way to do this is to use a blood glucose meter. If you have hypoglycaemia unawareness or you have a low blood sugar level often, a continuous glucose monitor may be a good option. This will measure your blood glucose level at regular times and will sound an alarm if your level drops below your target range.
  • Make sure you have a regular eating plan, including meals, snacks and drinks with enough carbohydrates to keep your glucose level within your target range. Have a source of fast acting carbohydrates with you at all times such as some juice or some sweets.
  • Check your blood glucose level before, during and after physical activity and adjust your medicine and carbohydrate intake accordingly.
  • Work with your doctor and healthcare team and follow any advice they have.

Types of hypoglycaemia

Hypoglycaemia usually happens to people who have diabetes when they have a mismatch of medicine, food or exercise. Non-diabetic hypoglycaemia is a rare condition and this is usually confirmed by seeing the classic signs and symptoms along with a low sugar level and seeing the symptoms decrease after a sugar intake.

There are two kinds of non-diabetic hypoglycaemia:

  • Reactive hypoglycaemia – This usually happens within a few hours of eating a meal. This may be when you are at risk of developing type 2 diabetes. Stomach surgery can make food pass into your small intestine too quickly. Also rare enzyme deficiencies can make it hard for your body to break down food.
  • Fasting hypoglycaemia – This may be related to a more serious condition. Alcohol can cause this especially if binge drinking. Certain medication, for example aspirin and certain antibiotics, can cause this. Low levels of certain hormones can affect blood glucose levels. Tumours such as a tumour in the pancreas, which is where insulin is made, can also be a cause.

The symptoms of non-diabetic hypoglycaemia include:

  • Shaking.
  • Feeling sleepy or drowsy.
  • Feeling hungry.
  • Confused or nervous.
  • Anxious.
  • Sweaty.
  • Irritable.
  • Loss of consciousness.
  • Difficulty speaking.

You should speak to you GP if you have symptoms of non-diabetic hypoglycaemia.

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About the author

Claire Vain

Claire Vain

Claire graduated with a degree in Social Work in 2010. She is currently enjoying her career moving in a different direction, working as a professional writer and editor. Outside of work Claire loves to travel, spend time with her family and two dogs and she practices yoga at every opportunity!

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