AIMS: The aim of this study is to determine the prevalence of impaired awareness of hypoglycaemia (IAH) and examine risk factors for IAH in adults with type 1 diabetes. METHODS: We conducted a population-based registry study of 10,202 adults (≥18 years) with type 1 diabetes using data from the Norwegian Diabetes Register for Adults. The registry used the 1-item Gold scale, measuring hypoglycaemia symptom awareness. We calculated the overall prevalence of IAH (Gold score ≥4) (95% CI) and prevalence for subgroups based on demographic and clinical variables. We estimated IAH prevalence based on continuous scales of age, diabetes duration and HbA RESULTS: Overall, 18.0% reported IAH (95% CI 17.2, 18.7). The prevalence increased linearly with the participants' age, whereas the associations of diabetes duration and HbA CONCLUSIONS: In this nationwide study, the IAH prevalence was 18.0%. Multiple hypoglycaemic events, female sex and diabetes duration were identified as important risk factors for IAH. Study findings highlight the complexity of self-reported hypoglycaemia symptom awareness and emphasise the importance of routinely addressing symptom awareness in diabetes follow-up.