AIM: Several wordings of the definition of severe hypoglycaemia (SH) exist. This study aims to evaluate how different SH definition wordings affect SH history assessment. METHODS: In this cross-sectional study, surveys were emailed to registrants of the T1D Exchange, a U.S. national type 1 diabetes patient registry. Participants' demographic information was collected. Six-month SH history was evaluated with questionnaires including SH definition wordings from either (1) professional societies, (2) a diabetes community website, or (3) a hypoglycaemia research questionnaire. Analyses included the McNemar test, pairwise Wilcoxon signed-rank test, logistic regression analysis, Kappa statistics, and Spearman correlation. RESULTS: A total of 1580 valid responses were obtained from participants (52% female; mean��������SD age: 46��������15���years; 95% White; mean��������SD diabetes duration: 25��������16���years). Questionnaires with four different SH definition wordings yielded significant variations in the prevalence of SH (i.e., having developed at least one episode of SH) and the number of SH episodes: the ADA/ENDO 2013 definition wording yielded the highest results on both metrics, whereas HypoA-Q and ADA 2023 yielded the lowest. Among participants reporting at least one SH episode, the number of episodes identified with the different SH definition wordings was poorly correlated (R: 0.09-0.37; p���<���0.001). Race, education level, and household income were associated with higher odds of discrepancies in SH history (p���<���0.05). CONCLUSION: This U.S. national survey with individuals living with type 1 diabetes demonstrated significant discrepancies in SH history when assessed with different SH definition wordings. Race and socioeconomic status were associated with these discrepancies.
