It is known that hypoglycaemia affects various domains of cognitive function. One aspect of cognitive function is 'social cognition', which is our ability to interpret facial expressions, gestures and speech. It is an approach to understanding human judgement and behaviour. There is anecdotal evidence for negative behavioural responses such as aggressiveness and argumentativeness during hypoglycaemia and while research has shown that hypoglycaemia can cause significant changes in mood, little information exists regarding its effect on social cognition. It is therefore not known whether hypoglycaemia affects this aspect of cognitive function but, if it did, it could explain why people with low blood sugar due to insulin treatment are often resistant to offers of help (for example, they may misinterpret a friendly gesture as being threatening). Knowledge of this effect of hypoglycaemia can be used to educate relatives and carers of people with diabetes who may suffer this problem.