Hypoglycaemia: A Beginner-Friendly Start
Hypoglycaemia: the few things that matter most, and the mistakes that catch people out early.
Blood glucose falling too low, usually in people taking insulin or sulfonylureas.
Key takeaways
- Commonly defined as: below 4 mmol/L
- Early symptoms: shakiness, sweating, hunger, anxiety, palpitations
- Most useful single change: Carry fast-acting carbohydrate at all times.
- Commonest mistake: Driving with glucose below 5 mmol/L.
- See a doctor if any of the signs under "When to speak to a doctor" below apply to you.
Why bother
It can develop quickly, impairs judgement exactly when judgement is needed, and is dangerous while driving.
Start here
These two first. Everything else is easier once they are habit.
- Carry fast-acting carbohydrate at all times
- Test before driving and every two hours on a long journey
Then add these
Once the first two are automatic, these are worth adding.
- Follow up treatment with a longer-acting carbohydrate
- Tell people around you what to do
The numbers, in one place
| Measure | Figure |
|---|---|
| Commonly defined as | below 4 mmol/L |
| Early symptoms | shakiness, sweating, hunger, anxiety, palpitations |
| Immediate treatment | 15-20g of fast-acting carbohydrate |
| Recheck after | 15 minutes, and repeat if still low |
| Driving rule | do not drive below 5 mmol/L |
Common early mistakes
- Driving with glucose below 5 mmol/L
- Treating with chocolate or biscuits, which act too slowly
- Ignoring repeated episodes rather than reviewing treatment
Where to go next
- Popular Beliefs About Hypoglycaemia, and What Is Actually Published
- Hypoglycaemia: The Questions People Actually Ask
- Hypoglycaemia — the reference entry
- Diabetic Eye Screening: Sorting the Evidence From the Noise
- Carbohydrates and Blood Glucose: Sorting the Evidence From the Noise
When to speak to a doctor
Call 999 if someone with diabetes becomes unconscious, has a seizure, or cannot swallow safely — do not put anything in their mouth. Seek medical advice for repeated episodes, for loss of the early warning symptoms, or if episodes occur overnight. In the UK you must inform the DVLA if you have had severe hypoglycaemia requiring help from another person.
Where this comes from
- NICE — Type 2 diabetes in adults: management
- Diabetes UK — hypos
How this page was put together
Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarised or generalised beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to a GP, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 999.
Spotted something wrong? Report an error on this page. We correct on the page and say what changed.
