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Hypoglycaemia (Hypos)

Hypoglycaemia, or ‘hypo’, means a low blood glucose of less than 4mmol/L.

Hypo can happen as a side effect of certain tablets and diabetes medicines such as insulin injections.

Always check with your GP, practice nurse, pharmacist or diabetes team what diabetes medicines you are taking. Ask if any of these medicines can put you at risk of a hypo.


Not everyone with type 2 diabetes is at risk – ask your GP about your risk.

Possible causes of a hypo include:

  • taking too much insulin or diabetes tablets or taking them at the wrong times
  • eating too little carbohydrate food, missing or delaying a meal or snack
  • doing more physical activity than usual
  • drinking alcohol, especially without eating
  • hot weather

Warning signs and symptoms

Warning signs or symptoms of a hypo may vary between people.

Signs can include:

  • weakness
  • sweating
  • tingling of lips and tongue
  • tiredness or sleepiness
  • feeling hungry
  • trembling and feeling shaky
  • dizziness
  • headache
  • blurred vision
  • difficulty concentrating
  • being anxious or irritable


It is important to know your own hypo signs.

Sometimes a hypo can happen without any symptoms, but it still needs to be treated.

Some of these symptoms also happen when you have high blood glucose levels. You should test your blood glucose to confirm if you are having a hypo.

What to do if you have a hypo

If you think you are hypo, check your blood glucose with your blood glucose meter.

If it is below 4, treat it with 15g of fast-acting carbohydrate.

If you do not feel able to check your blood glucose, take 15g of fast-acting carbohydrate immediately.

Step 1 - Treat the hypo with 15 grams of carbohydrate

Examples of 15g fast-acting carbohydrate are:

  • 5 glucose or dextrose sweets such as ‘Dextro Energy’, ‘Lucozade Energy’ or ‘Lift’ tablets (available from your pharmacy)
  • 170mls of Lucozade Original
  • Lift Glucose Juice Shot (60ml)

Be aware that 1 glucose tube such as ‘Glucogel’ has 10g of carbohydrate.

If glucose is not available, other options include:

  • 1 glass of fruit juice
  • 1 glass of a fizzy drink (not diet) - check the carbohydrate content
  • 3 teaspoons of sugar - for example, dissolved in hot water or tea

High fat foods such as chocolate and biscuits are not as fast-acting as those listed above.


Always check the amount of carbohydrate (sugar or glucose) in whichever product you use to treat a hypo. The amount in different fizzy drinks, glucose tablets or gels may change over time. Check the amount needed to give you 15g of carbohydrate.

Step 2 - Retest your blood glucose after 15 minutes

If your blood glucose level is still below 4, repeat the treatment by taking a further 15g of fast acting carbohydrate. Do this even if your symptoms have improved.

If your blood glucose is over 4 and you are not due to eat for hours, have a carbohydrate snack. For example, a piece of fruit, some plain biscuits or a slice of bread. Or have the next meal earlier and include some carbohydrate.

Step 3 - Try to figure out why the hypo happened and discuss it with your diabetes care team

Take a moment to consider when and why the hypo happened. This can help you to prevent it happening in future. If you are having hypos regularly, talk to your GP.

If you take insulin

If you use insulin to treat type 2 diabetes, ask your team if you need to use and store glucagon injections to treat hypos.

Support from the Long Term Illness Scheme and tax relief

A range of hypo treatments are available through your pharmacy. If your hypo treatment is prescribed by your GP or clinician it may be available under the Long Term Illness (LTI) scheme. Check with your pharmacy what is currently available under the LTI scheme.

People with diabetes may be able to claim tax relief on the cost of ‘hypo’ treatments as part of their health expense annual return. Ask your local tax office or for more information.

Tips for those at risk of a Hypo

  • Check your risk by asking if your diabetes medicines could cause hypos
  • Be prepared - carry some form of fast-acting carbohydrate or glucose at all times
  • Have your blood glucose meter to hand to check your blood glucose
  • Carry ID to let people know you have diabetes in case of emergency - you could keep this in a purse or wallet, or wear engraved jewellery (for example, a bracelet or necklace)
  • In your mobile phone, save a contact name as ICE to be called In Case of Emergency (ICE) or use the Medical ID function available on some mobile phones
  • Have regular meals
  • If exercising or more active than usual, consider your need for extra snacks

If you drink alcohol, the risk of a hypo increases if you are treated with insulin or some medicines. Use alcohol in moderation and avoid drinking on an empty stomach. Take a carbohydrate snack, especially before going to bed. Check your blood glucose before and after drinking alcohol to make sure you are safe.

Diabetes and alcohol

Hypoglycaemia and driving

If you use insulin or medicines that have the potential to cause hypos, you must take extra care when you drive.

Follow the National Driver License Service (NDLS) guidelines to help manage diabetes, check your blood glucose levels and drive safely.

Driving and type 2 diabetes

Blood glucose testing

Download our leaflet on treating and preventing hypoglycaemia (PDF, size 612 KB,2 pages)

Page last reviewed: 1 August 2020
Next review due: 1 August 2023

This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 9.