To investigate the characteristics of people with insulin-treated diabetes, who have experienced severe hypoglycaemic events (SHEs), in Germany, Spain or UK. Patients with type 1 (n=319) or insulin-treated type 2 diabetes (n=320) who had experienced ≥ 1 SHE in the preceding year were enrolled. Their median age was 53 years (range, 16-94 years). Data were collected using a questionnaire administered by an experienced interviewer. The median number of reported SHEs was 2-3 in 12 months. Most events (69%) occurred at home, usually during the day or evening (74%) and most commonly due to insufficient food consumption (45%). In patients whose hypoglycaemia awareness was tested, 68% had normal awareness. Patients requiring emergency healthcare treatment frequently had impaired hypoglycaemia awareness, and developed hypoglycaemic coma more often. Hospital treatment was usually provided in an emergency department (72-94%). The duration of stay was longest in Germany. Following a SHE, patients receiving professional treatment were more likely to: consult their physician, test their blood glucose more often, adjust insulin dose and receive self-management training. This survey of diabetes patients aged 16-94 years showed that SHEs represent a substantial burden on national healthcare systems in Germany, UK and Spain. The pattern of occurrence and treatment was similar in all three countries, despite differences in cultures and healthcare systems.