Hypoglycaemia

Hypoglycaemia - Recognising a low glucose level and responding with confidence

Clinical review September 2026

Hypoglycaemia, or a “hypo”, means blood glucose has fallen low enough to need action. It is most common in people using insulin or certain glucose-lowering medicines. The body is built to defend its fuel supply, so the early warning system can feel remarkably persuasive: shaking, sweating, hunger, palpitations, blurred vision, irritability or difficulty thinking clearly. It is biology sounding an alarm, not a failure of willpower.

Why lows happen

Glucose-lowering treatment, food, activity and alcohol all need to stay in conversation. A hypo can follow more insulin than the body needs, a missed or delayed meal, unexpected activity, alcohol, illness or a change in kidney function. Sometimes no clear cause is obvious at first; patterns found on glucose monitoring, a diary or a dose review are more useful than blame.

Symptoms vary and may change over time. Some people lose warning symptoms after frequent hypos, a situation called impaired awareness. That is a reason to discuss targets and treatment urgently with the diabetes team because severe hypos can become more likely.

Treat the low first

For a conscious adult who can swallow safely, UK diabetes education commonly advises taking 15–20 g of fast-acting carbohydrate, such as glucose tablets, glucose gel, a small sugary drink or fruit juice, then rechecking glucose after 10–15 minutes if monitoring is available and repeating if still low. Once recovered, a longer-acting carbohydrate snack or the next meal may be needed if it is not soon due. Individual plans, especially for people using automated insulin systems, should take priority.

Do not give food or drink to someone who is unconscious, having a seizure or unable to swallow safely. Use prescribed glucagon if available and you are trained, and call emergency services. Someone who has needed help for a severe hypo should have treatment reviewed promptly.

Prevention is a partnership with the plan

Keep rapid carbohydrate accessible, tell friends or colleagues what a hypo looks like, and carry medical identification where useful. Review patterns around exercise, alcohol and driving with the diabetes team; driving rules and testing requirements are specific and important. Do not drive if glucose is low or you feel a hypo beginning. Alcohol can cause delayed hypos, particularly overnight, so food, monitoring and an individual plan matter.

Hypoglycaemia without diabetes medication is less common and deserves medical assessment, particularly if episodes are recurrent or severe. A home glucose result can be helpful but needs interpreting with symptoms and context. The solution is not to eat continuously in case the body stages a surprise coup; it is to work out why the alarms are sounding.

What to bring to a review

A list of episodes, timing, glucose readings, food, activity, alcohol, medicines and whether help was needed can uncover a pattern. Future pages could cover hypos and exercise, nocturnal hypos, glucagon, diabetes technology and driving safely.

Important safety note

This page is for general education and cannot replace individual medical advice. Seek urgent help for severe symptoms, possible pregnancy with pain or bleeding, collapse, confusion, seizure, or any situation in which you feel acutely unwell. A clinician who knows your history can help tailor investigation and treatment.