Hypoglycaemia has many possible causes, although similar symptoms in each case can make diagnosis of the cause complex. Common early warning signs of hypoglycaemia include blurred vision, dizziness, shakiness, sweating, irritability, nausea and palpitations, progressing to confusion, syncope, headache and disturbances of vision. Loss of consciousness and convulsions may follow if corrective steps are not taken to increase blood glucose concentration. In rare cases death may occur if blood glucose remains low for 12 hours or more, as brain function is reduced and cannot be sustained. However, death from hypoglycaemia is avoidable. Causes of non-diabetic hypoglycaemia are an under-reported area in the nursing and wider literature. This article aims to help nursing staff recognise the types and causes of this condition.