Résumé
Background and Aims: Time below range from continuous glucose monitoring (CGM), is widely used to assess hypoglycaemia risk. However, its relationship with personal experience of hypoglycaemia is unclear. We investigated the association between time <3.9 mmol/l (TBR3.9) and person‐reported hypoglycaemia; symptomatic episodes that resolved on carbohydrate ingestion and/or a measured glucose ≤3.9mmol/l.Methods: This analysis included 401 adults with insulin‐treated diabetes (n = 204 with type 1 diabetes (T1D); n = 197 with type 2 diabetes (T2D)), who reported ≥1 hypoglycaemic episode in the past 3 months. For 10 weeks, they wore blinded CGM and recorded person‐reported hypoglycaemia in real time using the Hypo‐METRICS app. Data were analysed using generalised linear regression.Results: Participants had a median (IQR) age 58 (47‐66) years and 45% were women. HbA1c was 7.4% (6.8‐8.0%), 23% had impaired awareness of hypoglycaemia, and 43% used capillary glucose monitoring only. During 658,802 hours of CGM, TBR3.9 was 3.0% (1.1‐5.9%) and 11,600 person‐reported hypoglycaemia episodes were recorded. Using a generalised linear regression model, TBR3.9 explains 25% of the variation of person‐reported hypoglycaemia (21% in T1D, 12% in T2D). With every 1% change in TBR3.9, the weekly rate of person‐reported hypoglycaemia changes by 9.4% (p < 0.0001), with a 6.2% change in T1D (p < 0.0001) and 9.4% change in T2D (p < 0.0001).Conclusions: While TBR3.9 is a valuable tool to understand hypoglycaemia risk, it explains a relatively small proportion of the variation in person‐reported hypoglycaemia rates and highlights the limitation of using this metric as a surrogate marker for the experience of hypoglycaemia by the person living with diabetes.