Hypoglycaemia

Overview

Hypoglycaemia (say: hy-po-gly-SEE-mee-a) means your blood sugar has dropped too low. Blood sugar, also called blood glucose, is the main fuel your body and brain use. When it falls below a healthy level, usually under about 4 mmol/L, your body sends out warning signals and your brain starts to struggle. Most often this happens to people with diabetes who take insulin or certain diabetes tablets, but it can sometimes have other causes.

Yes, it is common among people with diabetes who use insulin or certain diabetes tablets — many people have mild episodes from time to time. In people without diabetes it is much less common.

It mostly affects people with type 1 diabetes, and people with type 2 diabetes who take insulin or certain tablets that lower blood sugar. It can also happen, more rarely, in people without diabetes — for example after long periods without eating, after heavy drinking, with some liver or hormone problems, or in pregnancy.

Symptoms

Common symptoms

• Shaking or trembling
• Sweating, often clammy and cold
• Feeling very hungry
• A fast or pounding heartbeat
• Feeling dizzy, lightheaded or weak
• Pale skin
• Tingling or numbness around the lips or tongue
• Feeling irritable, anxious or tearful
• Trouble concentrating or feeling confused
• Blurred vision
• Feeling very tired or sleepy

Symptoms in children

• Young children may not be able to explain what is wrong
• Sudden tantrums, crying or clinginess
• Being unusually quiet, sleepy or difficult to wake
• Pale, sweaty or shaky
• Refusing food or behaving out of character
• Night-time lows can cause bad dreams, crying out, or waking up soaked in sweat

Symptoms in older adults

• Confusion or muddled thinking may be the first sign
• Dizziness and falls
• Weakness or feeling unsteady on the feet
• Fewer early warning signs, so it can be missed
• Symptoms that can be mistaken for a stroke, dementia or simply 'old age'
• Some diabetes medicines raise the risk of lows more in later life

Causes

Main causes

• Taking too much insulin or too much of a diabetes tablet that lowers blood sugar
• Missing, delaying or eating less of a meal than usual
• Being more physically active than usual without adjusting food or medicine
• Drinking alcohol, especially on an empty stomach
• Being unwell, for example with vomiting or diarrhoea, so you eat less than usual
• Some medicines, including certain tablets for diabetes, heart or blood pressure problems
• In people without diabetes: long gaps without food, heavy drinking, liver or hormone problems, or problems with the pancreas

Risk factors

• Having type 1 diabetes
• Taking insulin or certain diabetes tablets
• Tight blood sugar control, which is good for long-term health but can raise the chance of lows
• Being older, or having kidney problems — medicines can stay in the body longer
• Drinking alcohol regularly
• Exercising hard or for a long time
• Being pregnant
• Having had a severe low before — this makes another one more likely
• Not being able to notice the early warning signs (sometimes called 'reduced awareness')

When to see a doctor

See a doctor urgently if:

• You have had a low that someone else had to help you treat
• You are having lows often, or at the same time each day
• Your early warning signs have become weaker or disappeared
• You have low blood sugar at night, or wake with headaches and sweats
• You have low blood sugar and you do not have diabetes
• You are pregnant and having lows
• You are worried about driving safely because of lows

Book a routine appointment if:

• You want to review your diabetes medicines or your blood sugar targets
• You would like to learn more about spotting and treating lows
• You want advice about food, exercise and alcohol
• You are planning a long trip, a new exercise programme, or a change in routine

Diagnosis

Your doctor will ask about your symptoms, when they happen, what you had eaten, and what medicines you take. They will want to know your blood sugar level at the time of symptoms. In many cases, a home blood sugar meter or a sensor you wear on your arm or tummy gives the answer. If the cause is unclear, or you do not have diabetes, your doctor may arrange blood tests.

Tests that may be done

• A finger-prick blood sugar reading taken when you feel unwell
• A continuous glucose monitor reading, if you use one
• A blood test from your arm to confirm a low level
• A review of all your medicines, including ones bought over the counter
• Blood tests to check your liver, kidneys, thyroid and hormone levels if the cause is not clear
• In specialist care, a supervised fasting test to see how your body handles not eating

What to expect at your appointment

Most people are diagnosed from their story plus a blood sugar reading, so it is often quick. If further tests are needed, they are usually simple blood tests. Keep a note of your readings, symptoms and what you ate beforehand — this helps your doctor spot patterns and make a plan that suits you.

Treatment

The aim is to bring your blood sugar back to a safe level quickly, and then to work out why it dropped so it can be prevented next time. Mild lows are treated with a small amount of fast-acting sugar, followed by a snack or meal. If lows keep happening, your care team will look at your medicines, meals, activity and daily routine together.

Self-care at home

• Learn your own early warning signs and act on them straight away — do not wait
• Carry fast-acting sugar with you at all times, such as glucose tablets, a small carton of juice, or sugary sweets
• Treat with fast-acting sugar first, wait about 10 to 15 minutes, then check your level again
• Once your level is back to normal, eat a snack or your next meal so it does not drop again
• Always carry some form of diabetes ID, such as a card, bracelet or phone note, so others know what to do
• Tell friends, family and colleagues where you keep your sugar and how to help
• Check your blood sugar before driving and follow your local driving rules
• Avoid drinking alcohol on an empty stomach, and check your level before bed after drinking
• Keep a simple record of when lows happen, so you can spot patterns

Medical treatments

Treatment is about adjusting what you already do, rather than starting something new. Your care team may review your diabetes medicines and the times you take them, change your blood sugar targets slightly, or give you practical advice about meals and activity. Structured education courses teach people how to match food, activity and medicine, and they are very effective. If you have severe lows, especially at night, your team may prescribe a rescue treatment that a family member or friend can give if you cannot swallow — they will show them exactly how and when to use it. For lows caused by something other than diabetes, the focus is on treating the underlying cause.

When is surgery considered?

Surgery is not a treatment for low blood sugar. Very rarely, a scan may find a growth in the pancreas that is producing too much insulin, and an operation may then be needed. Your specialist team would discuss this with you fully.

Living with this condition

With a little planning, most people live full and active lives with occasional lows. The key habits are eating regularly, carrying sugar, checking your levels when things change, and telling the people around you what to do. Many people find that keeping a small kit in each bag and at home takes away a lot of the worry.

Lifestyle tips

• Eat meals at regular times and do not skip them
• Plan ahead for exercise — check your level before, during and after, and adjust food or medicine with advice from your team
• Be careful with alcohol, and always eat something with it
• Take extra care when you are unwell — you may need to check your levels more often
• Wear or carry diabetes ID
• Keep fast-acting sugar within arm's reach, including by your bed
• Store spare supplies at work, in the car and at friends' homes
• Get your eyes, feet, kidneys and blood pressure checked as advised

Diet and exercise

There is no special diet for preventing lows, but regular meals that include starchy foods, fibre, and some protein help keep levels steady. If you exercise, check your blood sugar before you start and take fast-acting sugar with you. Longer or harder sessions can lower blood sugar for many hours afterwards, sometimes overnight, so a bedtime check is wise. A dietitian can help you plan meals and snacks around your routine.

Mental health and emotional wellbeing

Lows can be frightening, both for you and for the people who care about you, and worries about having one can affect sleep, work and confidence. This is very common and worth talking about — your care team can help you feel more in control. If you ever feel unable to cope, or have thoughts of harming yourself, contact your local emergency number or a crisis support line in your country straight away. You deserve support, and help is available.

Prevention

Many lows can be prevented, though not every single one. Most prevention comes down to matching your food, activity and medicines, checking your blood sugar when things change, and knowing your early warning signs. If lows keep happening, tell your care team rather than simply putting up with them — adjustments can make a real difference.

Vaccines

There is no vaccine for low blood sugar. Keeping up to date with routine vaccinations, including flu and pneumonia jabs if offered, helps you stay well and reduces the chance of illness upsetting your blood sugar.

Screening programmes

There is no national screening programme for low blood sugar. Instead, people taking insulin or certain diabetes tablets are usually offered regular reviews and structured education, which help spot problems early. If you have diabetes, attend your routine check-ups even when you feel well.

Complications

If left untreated

• Passing out, which can be dangerous depending on where you are
• Fits or seizures
• Injuries from falls or accidents
• Confusion that can be mistaken for drunkenness, which may delay help
• Night-time lows that disturb sleep and leave you exhausted
• Loss of the early warning signs if lows happen often
• In rare cases, long-lasting effects on thinking and memory after very severe or repeated episodes

Long-term outlook

The outlook is good for most people. Mild lows usually settle within minutes with a little sugar, and the risk can be greatly reduced by working with your care team on a plan that fits your life. If you have severe or frequent lows, tell your doctor — there is usually something that can be changed, and most people go on to feel confident and in control again.

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