Hypoglycaemia

Hypoglycaemia is a condition where blood sugar drops below safe levels, causing symptoms that range from shakiness and sweating to confusion and, in severe cases, loss of consciousness. While most common in people with diabetes who take insulin or certain medications, understanding how to recognize and treat low blood sugar quickly can prevent serious complications.

Table of contents

• What is hypoglycaemia?
• Signs and symptoms
• Causes and risk factors
• How is it diagnosed?
• Treatment and immediate care
• Prevention strategies

What is hypoglycaemia?

Hypoglycaemia is a condition in which your blood sugar, also called glucose (the body’s main source of energy), drops below the normal range. Glucose comes mainly from the carbohydrates in food and drinks you consume, and your blood carries it to all of your body’s cells to use for energy^[1].

For many people with diabetes, hypoglycaemia means a blood glucose reading lower than 70 milligrams per deciliter (mg/dL), or 3.9 millimoles per liter (mmol/L). For people without diabetes, it typically means a blood sugar level below 55 mg/dL or 3.1 mmol/L^[2]. However, your personal threshold might be different, so it’s important to check with your healthcare provider to find out what level is considered low for you^[3].

Glucose is particularly important because it’s the primary source of energy for your brain. Without enough glucose, your brain cannot function properly, which is why low blood sugar can cause serious symptoms and requires immediate treatment^[2].

Hypoglycaemia is very common in people with diabetes, especially those with Type 1 diabetes (a condition where the body doesn’t produce insulin). One large study found that 4 in 5 people with Type 1 diabetes and nearly half of all people with Type 2 diabetes (a condition where the body doesn’t use insulin properly) who take insulin reported a low blood sugar episode at least once over a four-week period^[2].

While hypoglycaemia is most often related to diabetes treatment, other medications and various medical conditions can also cause low blood sugar in people who don’t have diabetes, although this is uncommon^[1].

Signs and symptoms

Symptoms of hypoglycaemia can start quickly and vary from person to person. The same person may also experience different symptoms during different episodes^[2]. Understanding your own warning signs is crucial for taking action before blood sugar drops dangerously low.

When blood sugar levels become too low, your body releases a “fight-or-flight” hormone called epinephrine (also known as adrenaline). This hormone triggers many of the early warning symptoms you might notice^[16].

Common early signs of hypoglycaemia include:

• Feeling shaky or trembling
• Sweating and chills
• Weakness or fatigue
• Faster heartbeat or heart palpitations
• Extreme hunger
• Dizziness or lightheadedness
• Anxiety, nervousness or irritability
• Headache
• Confusion or trouble concentrating
• Pale skin (color draining from your face)
• Tingling or numbness in your lips, tongue or cheeks
• Nausea^[1][2]

These early symptoms are unpleasant, but they provide important warnings that you should take action before your blood sugar drops further^[2].

As hypoglycaemia worsens, more serious signs and symptoms can develop:

• Blurred or double vision
• Slurred speech
• Clumsiness or difficulty with coordination
• Unusual behavior, such as inability to complete routine tasks
• Feeling very weak
• Severe confusion^[1]

In cases of severe hypoglycaemia (when blood sugar drops below 54 mg/dL or 3.0 mmol/L), a person may experience:

• Seizures or fits
• Loss of consciousness (becoming unresponsive)
• Nightmares, if asleep^[1][6]

Some people with diabetes who have frequent low blood sugar episodes may develop hypoglycaemia unawareness, a condition where they don’t experience the usual warning symptoms when their blood sugar is low. This makes it harder to treat low blood sugar early and increases the risk of having severe episodes. This is more likely to happen if you have had diabetes for more than 5 to 10 years, often have low blood sugar, or take certain medicines such as beta blockers for high blood pressure^[8].

Low blood sugar can also occur during sleep, known as nighttime hypoglycaemia. You may wake up when this happens, but you shouldn’t rely on waking up. A continuous glucose monitor (a device that checks blood sugar levels throughout the day and night) can alert you if your blood sugar gets low while you’re sleeping^[8].

Causes and risk factors

Hypoglycaemia in people with diabetes most commonly happens as a side effect of insulin or certain other diabetes medications. These medicines lower blood sugar to treat diabetes, but they can sometimes make it go too low^[5].

Several factors can cause or contribute to low blood sugar in people with diabetes:

• Taking too much insulin or diabetes medication
• Skipping or delaying a meal or snack
• Not eating enough carbohydrates (the main source of glucose)
• Getting more physical activity or exercise than usual
• Drinking alcohol, especially without eating carbohydrates
• Being sick and unable to eat enough food or keep food down
• Accidentally injecting the wrong type of insulin^[1][4][23]

Exercise burns carbohydrates and increases your body’s sensitivity to insulin, which can lead to low blood sugar. This is why it’s important to plan around physical activity and adjust your meals or insulin accordingly^[6].

You are at higher risk of developing hypoglycaemia if you:

• Have Type 1 diabetes
• Take insulin or certain diabetes medications, particularly sulfonylureas (medications that help your pancreas release insulin) or meglitinides
• Are age 65 or older
• Have had low blood sugar episodes before
• Have other health problems such as kidney disease, heart disease, or problems with thinking and memory^[3][2]

Although it’s rare, people without diabetes can also experience hypoglycaemia. This can happen due to conditions such as liver disease, kidney disease, or hormone deficiencies (lack of certain hormones). It can also occur in people who have had certain types of weight loss surgery. Some medications, such as certain heart medicines and antibiotics, can cause low blood sugar as well^[7].

How is it diagnosed?

If you have diabetes and experience symptoms of hypoglycaemia, you should check your blood sugar level with a blood glucose meter (a small device that measures blood sugar from a drop of blood) or continuous glucose monitor if you can. If your reading is below 70 mg/dL, or whatever your healthcare provider has told you is too low, you need to treat it right away^[5].

Healthcare providers use what’s called the Whipple triad to diagnose hypoglycaemia. This means three things must be present:

• Documentation of low blood sugar
• The presence of symptoms
• The reversal of symptoms when blood sugar is restored to normal^[6]

If you have symptoms but use insulin or other diabetes medications to lower your blood sugar, your healthcare provider will likely conduct a physical exam and review your medical history. They will want you to keep a record of your blood sugar testing results and how you treated low blood sugar levels so they can review the information and help adjust your diabetes treatment plan^[9].

If you don’t use medications known to cause hypoglycaemia, your healthcare provider will want to know what symptoms you experienced and when. They may have you fast overnight or longer to allow low blood sugar symptoms to occur so a diagnosis can be made. In some cases, you may need an extended fast of up to 72 hours in a hospital setting. Your provider will draw blood samples to analyze your glucose levels, and if your symptoms occur after a meal, blood tests may be done after you eat^[9].

Treatment and immediate care

Hypoglycaemia needs immediate treatment. The faster you can raise your blood sugar, the better you’ll feel and the safer you’ll be.

If you have diabetes and your blood sugar is low, you should follow what’s called the 15-15 rule:

1. Eat or drink 15 grams of fast-acting carbohydrates (sugary foods or drinks that are quickly converted to sugar in the body)
2. Wait 15 minutes
3. Check your blood sugar again
4. If it’s still less than 70 mg/dL, repeat this process
5. Keep repeating these steps until your blood sugar is back in your target range^[13]

When treating low blood sugar, you need to absorb sugars as quickly as possible. Foods high in fiber (such as fruit, beans, or lentils) and foods high in fat (such as chocolate or baked goods) can slow down how fast you absorb sugars. Don’t eat foods containing peanut butter, nuts, or fats, as fat slows your body’s absorption of carbohydrates^[13][22].

Good options that provide about 15 grams of carbohydrates include:

• 4 ounces (½ cup) of fruit juice or regular (not diet) soda
• 1 tablespoon of sugar, honey, or syrup
• 3 to 4 glucose tablets
• 1 tube of glucose gel
• Hard candies, jellybeans, or gumdrops (check the food label for how much to eat)
• 5 Life Savers candies
• 12 gummy bears
• 6 large jelly beans^[13][21]

After your blood sugar returns to normal, eat a balanced snack or meal with protein and carbohydrates to keep your blood sugar stable. This could be some biscuits, a sandwich, or your next meal if it’s due^[5][13].

For young children, the amount needed may be less than 15 grams of carbohydrates, especially for infants and toddlers. Parents should ask their doctor how much their child needs^[13].

Treating severe hypoglycaemia

If blood sugar drops below 55 mg/dL, it’s considered severely low. At this level, you may not be able to treat it using the 15-15 rule. You also may not be able to check your own blood sugar or treat it by yourself, depending on your symptoms^[13].

If someone has very low blood sugar and becomes unconscious or unresponsive:

• Do not give them any food or drink, as they will not be able to swallow safely
• Put them in the recovery position (lying on their side)
• Give them a glucagon injection (a medication that raises blood sugar) straight away, if one is available and you know how to use it
• Stay with them until they’re fully recovered^[5]

Injectable glucagon is the best way to treat severely low blood sugar. A glucagon kit is available by prescription, and anyone at risk for severe hypoglycaemia should have one. Make sure your family and friends know how to use it. A person who faints due to severely low blood sugar will usually wake up within 15 minutes after a glucagon injection. If they don’t wake up within 15 minutes, they should receive one more dose^[13].

You should call emergency services (999 in the UK, 911 in the US) immediately if:

• You think someone has very low blood sugar and they’re not responding normally or they’re unconscious, and a glucagon injection is not available or you do not know how to use it
• You’ve given a glucagon injection and they have not recovered within 10 minutes
• They’ve been drinking alcohol^[5]

Contact a doctor for emergency medical treatment immediately after giving a glucagon injection, even if the person recovers^[13].

Prevention strategies

One of the best ways to prevent low blood sugar is to check your blood sugar levels regularly, especially if you have diabetes. Frequent monitoring helps you understand how your body responds to food, activity, and medications^[13].

If you take medicine for diabetes, there are several things you can do to reduce the risk of low blood sugar:

• Follow the treatment plan agreed with your diabetes care team, including adjusting your insulin dose when you need to
• Check your blood sugar regularly, especially before each meal and at bedtime
• Carry something with you that will raise your blood sugar quickly, such as sugary drinks, sweets, or glucose tablets
• Carry a glucagon injection kit and medical identification with you
• Make sure your family and friends know how to treat severe low blood sugar
• Ask your care team about getting a continuous glucose monitor if you don’t already have one
• If you have Type 1 diabetes and often have problems with low blood sugar, ask your diabetes care team about switching to an insulin pump^[5]

Important habits to prevent hypoglycaemia include:

• Do not skip or delay meals
• Eat regular meals and snacks throughout the day
• Do not drink too much alcohol, and never drink alcohol without eating
• If you’re planning to be more active than usual, have a snack before or during exercise
• If you think you’re at risk for low blood sugar overnight, have a snack before bed^[5][8]

Check your blood sugar often when low blood sugar episodes are more likely, such as when the weather is hot or when you travel^[13].

If you drive and have diabetes, you’ll need to check your blood sugar before each journey and then every 2 hours while driving. If you get low blood sugar, do not drive for at least 45 minutes after your blood sugar is back to normal^[5].

If you have diabetes and you get low blood sugar often, you’ve had severe episodes, or you’ve had episodes at night, see your doctor or speak to your diabetes care team. You may need changes in your diabetes meal plan, physical activity plan, or medications^[5][7].

If you don’t have diabetes but get symptoms of low blood sugar such as shaking, sweating, a fast heartbeat, and feeling confused, you should see your doctor. They can investigate the cause and recommend appropriate treatment^[5].