TBR is a widely used continuous glucose monitoring (CGM) metric representing glucose exposure below specific thresholds. However, it is unclear whether TBR reflects the actual number of hypoglycemic episodes experienced by individuals with type 1 diabetes (T1D). The Hypo-METRICS study, presented at the European Association for the Study of Diabetes (EASD) 2025, investigated the relationship between TBR and both sensor-detected and person-reported hypoglycemia events.

The analysis included 259 adults with T1D (median age 48 years; diabetes duration 21 years; 75% using CGM) who wore blinded CGM devices for up to 10 weeks and recorded hypoglycemia episodes through a smartphone app. Sensor-detected hypoglycemia was defined as glucose readings below 3.9 mmol/L or 3.0 mmol/L for ≥15 minutes, while person-reported episodes were identified by symptoms or measured glucose <4 mmol/L.

TBR correlated strongly with weekly sensor-detected hypoglycemia rates (r=0.97 for <3.9 mmol/L and r=0.96 for <3.0 mmol/L, both p<0.001), and moderately with person-reported events. Participants with ≤2% TBR<3.9 mmol/L had a median of 1.9 events/week, compared with 4.9 events/week among those with TBR 2–4%.
These findings confirm that TBR is a robust surrogate measure for hypoglycemia frequency, offering a practical tool for quantifying hypoglycemia burden and guiding glycemic management in people with T1D.