Prevalence of impaired awareness of hypoglycaemia in adults with Type 1 diabetes

Aims  Impaired awareness of hypoglycaemia (IAH) is thought to affect approximately 25% of people with Type 1 diabetes. While this estimate was based on retrospective information from patients in several small studies performed several years ago, validated methods of assessment have not been used in a large hospital clinic‐based population to ascertain the prevalence in the present era. Methods  Five hundred and eighteen people with Type 1 diabetes were recruited by random selection over a 2‐year period. Participants completed a questionnaire documenting baseline characteristics and assessment of their awareness status using the method described by Gold et al . The number of episodes of severe hypoglycaemia they had experienced in the preceding year was recorded retrospectively. Results  IAH was present in 19.5% of the cohort. Compared to those with normal awareness of hypoglycaemia, those with IAH were significantly older [mean ± standard deviation ( sd ); 39.3 ± 12.9 vs. 45.9 ± 13.5 years, P  < 0.001], had a longer duration of diabetes [median (interquartile range) 14 (8–22) vs. 23 (14–32) years, P  < 0.001], and had a six‐fold higher frequency of severe hypoglycaemia in the previous year [0.38 ± 1.04 (25th–75th centile 0–0) vs. 2.36 ± 4.81 (25th–75th centile 0–2) episodes per person, P  < 0.001]. Conclusions  The present survey of a large hospital‐based clinic population has confirmed that a significant proportion of people with Type 1 diabetes (19.5%) continue to have IAH. Despite improvements in insulin therapies, intensification of insulin regimens and innovative patient education, the prevalence of IAH remains high in Type 1 diabetes.