Low blood sugar, or hypoglycaemia, is the most common diabetic emergency a first aider will meet, and it can progress from mild symptoms to unconsciousness within minutes. It usually affects people who take insulin or certain tablets and who have taken too much medicine, missed or delayed a meal, exercised unusually hard or drunk alcohol. The treatment is simple and fast: sugar. Low blood sugar that is recognised and treated promptly usually resolves completely.
Signs of Low Blood Sugar
- Weakness, light-headedness, shakiness or giddiness
- Hunger, sweating and cold, pale, moist skin
- A rapid pulse and palpitations
- Confusion, poor concentration, blurred vision or slurred speech
- Irritability, aggression or behaviour that looks like drunkenness
- Drowsiness, seizures and loss of consciousness if untreated
Anyone with diabetes who looks unwell and confused should be treated for low blood sugar first.
Low Blood Sugar First Aid for a Conscious Person
- Sit the person down and stay with them.
- Give fast-acting sugar. About 15 to 20 grams is a good dose: glucose tablets or gel, a small glass of fruit juice or regular soft drink, jelly sweets or a heaped tablespoon of sugar or honey. Do not use diet or sugar-free drinks, saccharin or artificial sweeteners, which contain no sugar.
- Wait 10 to 15 minutes. Recheck how they feel, and measure blood glucose if they have a meter.
- Repeat the sugar if they are not improving.
- Follow with a snack of longer-acting carbohydrate, such as a sandwich, biscuits or fruit, once they recover.
- Seek medical help if they do not respond, if it happens repeatedly or if you are unsure.
If the Person Cannot Swallow or Becomes Unconscious
Never put food or drink into the mouth of someone who cannot swallow safely. Turn them onto their side into the recovery position, open the airway using the DRABC primary survey and call an ambulance. If the person has a prescribed glucagon injection and you are trained and authorised to use it, follow their plan while help is on the way.
What Causes Low Blood Sugar?
- Too much insulin or diabetes medicine
- Delayed or skipped meals
- Unplanned or intense exercise
- Alcohol, especially without food
- Illness with vomiting
People who do shift work, drive, work at height or operate machinery should have a plan for managing low blood sugar and carry fast sugar at all times.
Low Blood Sugar Compared With High Blood Sugar
Low blood sugar comes on quickly with cold, sweaty skin, while high blood sugar develops over hours or days with thirst and dry skin. If you cannot tell which it is, give sugar. See our overview of diabetes emergencies and the next guide on high blood sugar.
Preventing Low Blood Sugar Episodes
People who use insulin should match doses to meals and activity, check blood glucose before driving or working at height, and always carry fast sugar. Employers can help by allowing regular meal breaks and by making sure first aiders know the signs of low blood sugar and where glucose is stored. Anyone who has repeated episodes should see their doctor, because treatment doses may need adjusting.
Frequently Asked Questions
What if the person refuses sugar?
Explain calmly that the symptoms are caused by low blood sugar. If they remain confused or aggressive, call for medical help rather than force them.
How long until they feel better?
Usually 10 to 15 minutes after sugar. If not, repeat once and call an ambulance.
References and Further Reading
- NHS, Low blood sugar (hypoglycaemia)
- NHS, Diabetes
- American Heart Association and American Red Cross, Guidelines for First Aid
Last updated: November 2026
Prepared by: EHS Guidelines Editorial Team
This article is general educational information and is not a substitute for accredited first aid training or professional medical care. In an emergency, call your local emergency number immediately. Emergency numbers, medicines and protocols differ between countries, so follow local guidance.
Be the first to comment