Hypoglycaemia

Also called Hypo, Low blood sugar

Blood glucose falling too low. It can be corrected in minutes, and it kills people when it is not recognised.

Important: This page is general information, not medical advice, and it is not a diagnosis. If you are worried about your health or someone else's, speak to a GP, pharmacist, or call 111. In an emergency, call 999.

What it is

Hypoglycaemia is blood glucose below 4 mmol/L. The rule taught to everybody with diabetes is four is the floor.

It happens in people treated with insulin or with certain tablets, usually because of too much insulin, a missed meal, extra activity, or alcohol.

The brain runs on glucose, so the effects escalate quickly: from shakiness and sweating, to confusion and aggression, to seizure and unconsciousness.

The part that matters most in care settings is that a hypo does not look like a medical emergency. It looks like somebody being difficult. Confusion, slurred speech, aggression and poor coordination in a person with diabetes is a hypo until proved otherwise, and treating it as behaviour has killed people.

Signs you might notice

Early: shaking, sweating, hunger, palpitations, anxiety, tingling lips.

Then: confusion, difficulty concentrating, slurred speech, poor coordination, unusual behaviour, aggression or tearfulness.

Then: seizure, loss of consciousness.

Impaired hypoglycaemia awareness is a specific danger: after many hypos the warning symptoms disappear, and the first sign is confusion or collapse.

Night hypos may show only as sweating, nightmares or a headache on waking.

How it can affect day-to-day life

Fear of hypos, particularly at night, leads people to run their glucose deliberately high, which causes long-term complications. That trade-off is rational and it deserves addressing rather than criticising.

Alcohol is a major risk: it blocks the liver's glucose release, and hypos can occur many hours later, overnight.

In care settings the two failure modes are giving insulin without food, and not recognising a hypo. Both are training issues.

Supporting someone well

Treat immediately with 15 to 20g of fast-acting carbohydrate: glucose tablets, 150ml of ordinary fizzy drink or fruit juice, or four to five jelly babies.

Wait 15 minutes, retest, and repeat if still below 4.

Then give longer-acting carbohydrate: a sandwich, biscuits, or the next meal.

Never give anything by mouth to somebody unconscious or fitting. Put them in the recovery position, give glucagon if you are trained and it is available, and call 999.

Do not use chocolate; the fat slows absorption.

Know where the glucagon is and who can give it.

Treat unusual behaviour in a person with diabetes as a hypo first, and test.

Fiducia Guardian holds the hypo plan, the insulin regime and who is trained in glucagon, so a school, a respite service and a family are all doing the same thing.

Where to get help

Call 999 for unconsciousness, seizure, or a hypo not responding to treatment.

Diabetes UK helpline: 0345 123 2399.

Frequent hypos or loss of warning symptoms needs an urgent diabetes team review, not a wait for the annual appointment.

Tools we make that might help

These are our own products. We have put them here because they do something specific for this condition, not because every page needs a list.

Fiducia Guardian

The hypo plan, insulin regime and who is trained in glucagon, shared across every setting.

Where to read more

Last reviewed 2026-08-28 by Fiducia Together · Next review due 2027-08-28