OBJECTIVES: Hypoglycaemia is one of the most frequent acute complications of type 1 diabetes. The fear and anxiety associated with experiencing hypoglycaemia may cause some diabetics to deliberately allow their blood sugar to become elevated in order to avoid future events, thus risking long-term diabetic complications. This trade-off between risks suggests that the psychological impact of hypoglycaemia on quality of life may be underestimated. This study's prupose is to quantify the impact of fear of hypoglycaemia on quality of life. METHODS: Eighty-five type 1 diabetics completed the Hypoglycaemia Fear Survey (HFS), and questions relating to the frequency and severity of hypoglycaemic events. Respondents were categorised by whether or not they had experienced a severe hypoglycaemic event in the past three months. Key differences on the HFS were used to construct five health states which described the behaviour, state of mind and events experienced during a typical week for a type 1 diabetic: baseline; fear of non-severe hypoglycaemia with and without a non-severe hypoglycaemic event; fear of severe hypoglycaemia with and without a severe hypoglycaemic event. A total of 122 people from the general population evaluated the five health states using the time-trade-off methodology. Short-term disutilities during events and long-term disutilities due to fear of future events were estimated as the differences between health state utilities. RESULTS: Fear of severe hypoglycaemia had a disutility value of –0.06 and fear of non-severe hypoglycaemia had a disutility value of –0.01. A severe hypoglycaemic event had a disutility value of –0.16, whilst the disutility associated with a non-severe hypoglycaemic event was –0.07. CONCLUSIONS: Fear of hypoglycaemia has a detrimental impact on quality of life in diabetic patients beyond that of the event itself. When comparing insulin therapies, the reduction in the incidence of hypoglycaemia should be incorporated as an important measure of treatment success.