Does hypoglycaemia cause fainting?

The brain needs glucose to work. When blood sugar falls, you may first notice sweating, shaking, hunger, dizziness, blurred vision, confusion or unusual behaviour. If the fall continues, awareness can become impaired and a person may lose consciousness. Fainting can also have other causes, so the episode should not be used to identify hypoglycaemia by itself.

If someone has fainted, do not give food or drink while they are unconscious because they could choke. Check that they are breathing and place them on their side if needed while help is arranged.

If the person is awake and able to swallow, use their diabetes action plan if they have one and take a quick source of glucose. Recheck symptoms after a short interval and eat a meal or snack when recovered if advised in the plan. Do not drive, swim or operate machinery while symptoms are present.

People who use insulin or medicines that lower blood sugar should ask their clinician how to treat an episode and whether a glucagon kit is appropriate. Keep a source of fast-acting glucose available and tell household members what to do.

Call emergency services if the person is unconscious, has a seizure, is not breathing normally, cannot swallow safely, remains confused, or does not recover promptly. Do not leave them alone. Urgent assessment is also needed after a first faint, repeated episodes, injury, chest pain, severe headache or trouble speaking.

Arrange medical review if episodes recur, happen without diabetes treatment, or follow a change in medicine, meals or exercise. A clinician can look for the trigger and reduce the chance of another episode.

Ask what glucose reading should prompt action, how to adjust treatment around exercise or missed meals, whether another medicine could be contributing, and when to use emergency glucagon. Record what you felt, what you ate, medicines taken and how quickly you recovered.