banner image

Reading Time: 8 minutes 55s

Hypoglycaemia (Low Blood Sugar)

Hypoglycemia, commonly known as a "hypo," is a condition where the glucose levels in the blood are abnormally low, below four millimoles a liter. This low glucose or sugar level means the body does not have sufficient energy for its usual activities.

Usually, hypoglycaemia is linked to diabetes, mainly occurring when a diabetic person takes excessive insulin, skips a meal, or over-exercises. Though rare, non-diabetic individuals can also get hypoglycaemia due to malnutrition, heavy alcohol consumption, or other conditions like Addison's disease.

By Able Health I Medically reviewed by Dr. Alireza Estedlal

Page last reviewed: February 2024 I Next review due: February 2026

Why does hypoglycaemia happen?

Hypos can result from an imbalance between the food you consume, the physical activity you engage in, and your diabetes medication, particularly insulin. Not all persons with diabetes will experience low blood sugar, but understanding the causes can help minimize the frequency of occurrence.

While the exact reasons why hypos develop are unclear, several factors can increase their likelihood, such as:

  • Delaying or missing meals or snacks
  • Insufficient carbohydrate intake at the previous meal
  • Engaging in intense exercise without consuming more carbohydrates or reducing insulin doses (for those taking insulin)
  • Taking additional insulin (or particular diabetes medications) than required
  • Alcohol consumption
  • Being ill
  • Stress or anxiety
  • Extreme weather changes

Insulin, as well as some diabetes medicines, can increase the possibility of developing hypoglycaemia. It's thus important to consult your diabetes medical team if you are uncertain if your treatment increases the risk of the condition.

Signs and Symptoms of Hypoglycaemia

Everybody experiences varying symptoms of hypoglycaemia, but the most common ones include:

  • Feeling shaky
  • Being confused
  • Sweating
  • Anxiety or irritability
  • Going pale
  • Palpitations and a rapid rhythm
  • A feeling of tingling lips
  • Blurry vision
  • Hunger
  • Feeling tearful
  • Exhaustion
  • Headaches
  • Lack of concentration
  • Night sweats

Sometimes, these symptoms are known as 'diabetic attack.' However, this term can as well be used to refer to other severe conditions, such as diabetic ketoacidosis (DKA).

Some individuals with diabetes might be at risk of having hypo unawareness. This is where there are no symptoms indicating a drop in blood sugar levels, a condition that could be dangerous.

Talk to our doctor if you’re concerned about symptoms

You can book an appointment with a private GP today for only £20*.

Book an appointment


Hypoglycemia usually arises when the glucose (blood sugar) level drops significantly, affecting the continuation of normal body functions. This can happen because of many reasons, and the most prevalent one is the medication side effect of drugs intended to manage diabetes.

Blood sugar regulation

The body breaks down the food we consume into glucose, which serves as the main energy source. Insulin, a hormone the pancreas produces, helps glucose get into the cells to provide the necessary fuel required. Any excess glucose is deposited in the muscles and liver in glycogen form.

Not eating food for several hours causes blood sugar levels to drop, and the body ceases insulin production. Instead, the pancreas releases another hormone known as glucagon, which signals the liver to break down stored glycogen and distribute glucose into the blood. This process maintains the blood sugar in a normal range till your next meal.

In addition, the body can produce glucose through a process that takes place primarily in the liver and also in the kidneys. During a lengthy fasting period, the body may break down fat deposits and utilize the breakdown products as an alternative energy source.

Possible causes with diabetes

Having diabetes means that you may either not produce insulin (type 1 diabetes) or your body could be less responsive to it (type 2 diabetes). This can cause glucose to accumulate in the bloodstream, sometimes reaching dangerously high levels. Therefore, to manage this, you can take insulin or medications to help reduce the levels of blood sugar.

However, taking excess insulin or other drugs for diabetes can result in a significant drop in blood sugar levels, leading to hypoglycemia. The condition can also be triggered by eating less than usual meals after your regular diabetes medication dose or engaging in more physical activity than you normally do.

Possible causes, without diabetes

Hypoglycemia in individuals who don't have diabetes is somewhat uncommon. Some of the possible causes are:

  • Medications: Accidentally taking another person's diabetes medicine can lead to hypoglycaemia. Other drugs could also result in low blood sugar, particularly in minors or those with kidney failure. An example is quinine (Qualaquin), which is intended to treat malaria.
  • Too much alcohol consumption: Heavy alcohol intake without eating could prevent the release of glucose into the bloodstream from its glycogen stores, leading to hypoglycemia.
  • Severe diseases: Critical liver conditions like hepatitis or cirrhosis, kidney disease, severe infections, and advanced heart disease might contribute to hypoglycaemia. Kidney problems can as well prevent the proper excretion of medications in the body. This leads to a collection of drugs that affect and lower the levels of blood sugar.
  • Prolonged starvation: Hypo can result from starvation and malnutrition when insufficient food intake depletes the body's glycogen stores needed to produce glucose. Anorexia nervosa is an example of an eating condition that can trigger hypoglycemia due to prolonged starvation.
  • Insulin overproduction: An uncommon pancreatic tumor (insulinoma) can lead to excessive insulin production, leading to hypoglycemia. Other tumors may also create insulin-like elements. Abnormal pancreas cells can as well produce too much insulin, and this can result in hypoglycaemia.
  • Hormone deficiencies: Some disorders of the adrenal or pituitary gland can lead to insufficient amounts of hormones regulating glucose release or metabolism. Minors with low growth hormone may develop hypoglycemia.

Who is at risk of hypoglycemia?

Diabetic individuals injecting insulin or taking particular diabetes pills (sulphonylureas) have an increased possibility of low blood glucose.

Other health conditions may cause excessive insulin production, leading to hypoglycemia even in those who don't take insulin or diabetes medications. So, if you experience any low blood glucose symptoms without using such medicines, it is essential to consult your doctor for more examination.

How to reduce your risk of low blood sugar

For people taking diabetes medication, these measures can help you minimize the possibility of low blood sugar:


  • Stick to the treatment plan recommended by the diabetes caregivers, including insulin dose adjustment when needed.
  • Regularly check blood sugar levels.
  • Carry things that can quickly boost your blood sugar, like sweets, sugary drinks, and glucose tablets.
  • Keep a glucagon injection kit as well as medical ID with you at all times.
  • Ensure your family and friends understand how to treat critically low blood sugar.
  • Consult your care team about obtaining a continuous glucose monitor or flash monitor in case you don't own one already.
  • For those with type 1 diabetes who frequently experience low blood sugar problems, discuss the possibility of changing to an insulin pump with your diabetes care providers.


  • Skip or delay your meals.
  • Drink excessive amounts of alcohol; adhere to the recommended rules of no more than 14 units of alcohol per week, distributed over at least 3 or more days.
  • Take alcohol without eating.

How is Hypoglycaemia Diagnosed?

Healthcare providers usually measure blood sugar levels using a glucose meter during hypoglycaemia diagnosis. A level of blood glucose that is less than 4.0 mmol/L signifies hypo. Urine tests, however, cannot detect the condition.

When undergoing a blood test is impossible or could take longer, it's advisable to start treating the hypoglycemia immediately.


How to treat low blood sugar yourself

For people who have diabetes and experience symptoms of hypo or have blood sugar lower than 4mmol/L, these steps may be helpful:

  • Consuming something that rapidly boosts blood sugar, like a small glass of sugary fizzy drink or fruit juice, 4 large jelly babies, 5 glucose or dextrose pills or 2 tubes of glucose gel.
  • Checking your blood sugar every 10 to 15 minutes.
  • Take another sugary drink or snack in case the blood sugar is still lower than 4mmol/L and measure again after ten minutes.
  • When the symptoms get better, and the blood sugar level is more than 4mmol/L, take something to help maintain your blood sugar rate up for an extended period, like a sandwich, biscuits, or the next scheduled meal.

How to treat severe low blood sugar

If a person has severely low blood sugar and is unconscious, do the following:

  • Avoid giving the foods or fluids since they won't swallow safely.
  • Turn them into the recovery position.
  • Administer glucagon injection immediately if it's accessible, and you know how to use it.
  • If they begin recovering within ten minutes after glucagon injection and are able to swallow safely, bring them foods or drinks that will help boost blood sugar.
  • Remain by their side until they recover fully.

Likewise, see a GP if you:

  • Are diabetic and frequently experience low blood sugar, have suffered from critical hypos, or have had low blood sugar at night.
  • Are diabetic and don't usually identify the symptoms of low blood sugar.
  • Don't have diabetes but experience symptoms of hypos like sweating, shaking, rapid heartbeat, or feeling confused.

It's highly important to seek advice from your diabetes care providers if you have diabetes.