Hypoglycaemia (hypos)

Hypoglycaemia (a hypo) happens when your blood glucose level is too low. You'll need to treat a hypo if your blood glucose falls below 4mmol/L.

This can happen when you:

Hypos come on fast. Be aware of the signs of a hypo so you can treat it quickly.

The most common signs are:

Treating a hypo

You need to treat a hypo quickly, before it gets worse.

Eat or drink something sugary, like:

Try not to eat:

Check your blood glucose after 10 minutes. If it's still low, eat something sugary again.

You may still have hypo symptoms as your blood glucose levels rise, so check your blood glucose rather than going by how you feel.


It's important your family and friends know what to do if you have a hypo and you cannot help yourself.

They should give you an injection of glucagon or call 999 and ask for an ambulance if you're not responding to them.

Emergency hypo treatment

Some people keep glucagon at home in case of an emergency. An injection of glucagon releases stored glucose from your liver.

Speak to your care team about whether you should keep glucagon at home and train family and friends to use it.

If you do not come round within 10 minutes of the glucagon injection, whoever you're with should call 999 and ask for an ambulance.

Read more about what to do if you're having a hypo on Diabetes UK

Not being aware of a hypo

Some people have no clear signs they're about to have a hypo. This can happen if you have had type 1 diabetes for a while.

It can be dangerous, particularly if you're driving, and puts you at risk of a severe hypo.

If this is happening to you, speak to your care team. It's often temporary.

It can help if you test your blood glucose more often to understand how you can raise it.

A continuous glucose monitor (CGM) or flash monitor lets you see your blood glucose levels at any time. It can help you take action more quickly to prevent hypos.

If you do not already have one, ask your care team about getting a monitor. You can usually get one free on the NHS.


Doing a diabetes course can help you reduce the number of hypos you have and how severe they are.

Hypos while sleeping

Hypos can happen while you sleep. If a hypo does not wake you up, there's a risk of you having a severe hypo.

You might be having night-time hypos if you feel very tired when you wake up, have a headache, or have damp bedding.

If you think you're having hypos while you sleep:

Page last reviewed: 7 July 2021
Next review due: 7 July 2024