Dealing with hyperglycaemia
High blood sugar
Peer reviewed by Dr Hayley Willacy, FRCGP Last updated by St John AmbulanceLast updated 20 Nov 2016
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In this series:Type 1 diabetesInsulin
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This leaflet is created from first aid advice provided by St John Ambulance, the nation's leading first aid charity. This advice is no substitute for first aid training - find a training course near you.
At a glance
Hyperglycaemia means high blood sugar, caused by too little insulin.
Symptoms include warm, dry skin, thirst, drowsiness, and fruity-smelling breath.
Untreated, it can lead to unresponsiveness, needing emergency treatment.
Call 999 or 112 immediately if you suspect hyperglycaemia.
If unsure if blood sugar is high or low, give something sugary.
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In this article:
Too little insulin can cause high blood sugar (hyperglycaemia).
If it's not treated and gets worse, the person can gradually become unresponsive (going into a diabetic coma). So it's important to get them to see a doctor in case they need emergency treatment.
Continue reading below
What to look for
Warm, dry skin.
Rapid pulse and breathing.
Fruity sweet breath.
Really thirsty.
Drowsiness, leading to unresponsiveness if not treated.
What you need to do
Back to contentsCall 999 or 112 straightaway for medical help and say that you suspect hyperglycaemia.
While you wait for help to arrive, keep checking their breathing, pulse and level of response.
If they lose responsiveness at any point, open their airway, check their breathing and prepare to treat someone who's become unresponsive.
Continue reading below
If you're unsure whether their blood sugar is high or low
Back to contentsIf you're not sure whether someone has high or low blood sugar, give them something sugary anyway, as this will quickly relieve low blood sugar and is unlikely to do harm in cases of high blood sugar.
If they don't improve quickly, call 999 or 112 for medical help.
If they lose responsiveness at any point, open their airway, check their breathing and prepare to treat someone who's become unresponsive.
Note: these hints are no substitute for thorough knowledge of first aid. St John Ambulance holds first aid courses throughout the country.
Adapted from the St John Ambulance leaflet: diabetic emergency. Copyright for this leaflet is with St John Ambulance.
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Frequently asked questions
What specifically causes the fruity sweet smell on someone's breath when they have high blood sugar?
The fruity sweet smell on a person's breath is a symptom of hyperglycaemia, which occurs when there is too little insulin in the body. While the article doesn't detail the exact biological process, it indicates it's a key sign to look for in suspected high blood sugar.
Why is it important to seek medical help quickly for high blood sugar?
It's important to seek medical help straightaway for high blood sugar because if it's left untreated and worsens, the person can gradually become unresponsive, which is known as going into a diabetic coma. Emergency treatment may be required to prevent this serious outcome.
What should I do if the person becomes unresponsive while I'm waiting for medical help?
If the person becomes unresponsive at any point while you are waiting for medical help to arrive, you should open their airway, check their breathing, and prepare to treat someone who has become unresponsive. You should also continue to monitor their breathing, pulse, and level of response.
Is there any harm in giving someone sugary food or drink if I'm not sure if their blood sugar is high or low?
If you are unsure whether someone's blood sugar is high or low, giving them something sugary is unlikely to cause harm in cases of high blood sugar. It will, however, quickly relieve low blood sugar, so it's a safe initial action if you're uncertain.
What does 'opening their airway' involve if someone becomes unresponsive?
The article advises to 'open their airway' if someone becomes unresponsive. While it doesn't provide specific instructions on how to perform this, it's a critical step in first aid for an unresponsive person, usually learned in a first aid course.
How can I tell if someone's breathing or pulse is rapid?
The article lists 'rapid pulse and breathing' as signs of high blood sugar. While it doesn't give specific rates or methods to check, a rapid pace would be noticeably faster than normal breathing and heart rate for that individual.
Can a person with high blood sugar suddenly feel better on their own without medical intervention?
The article indicates that high blood sugar (hyperglycaemia) needs to be treated, and if it worsens, the person can become unresponsive. This suggests that without medical intervention, the condition is unlikely to resolve on its own and can become more severe.
About the author
St John Ambulance
About the reviewerView full bio
Dr Hayley Willacy, FRCGP
General Practitioner, Medical Author
MBChB (1992), DRCOG, DFFP, MRCOG (Part 1) MRCGP (2007), DFSRH (2013), MSc - medical education (2020)
Dr Hayley Willacy was an NHS GP working in northwest England, who retired from clinical practice in 2022 after 30 years.
Article history
The information on this page is written and peer reviewed by qualified clinicians.
20 Nov 2016 | Latest version
6 Aug 2013 | Originally published
Authored by:
St John Ambulance
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