Aims/hypothesis: Severe hypoglycaemia events (SHE) remain frequent in people with type 1 diabetes despite advanced diabetes technologies. We examined whether time below range (TBR) 3.9 mmol/l (70 mg/dl; TBR70) or 3.0 mmol/l (54 mg/dl; TBR54) is associated with future SHE risk and whether impaired awareness of hypoglycaemia (IAH) modifies this relationship.
Methods: We analysed data from participants in the Study of the French-speaking Society of Type 1 Diabetes (SFDT1) who used continuous glucose monitoring. IAH was assessed using the Gold Score (≤2, no IAH; 3, undetermined; ≥4, IAH). SHE frequency was self-reported 12 months after inclusion. We analysed associations between TBR and SHE using logistic regression models adjusted for age, sex, social vulnerability and insulin treatment, including TBR-IAH interactions. We performed spline analyses to explore non-linear patterns.
Results: One-year incidence of SHE was 11.7% among 848 participants (mean ± SD age 41.6 ± 13.3 years; 53.8% female sex, HbA1c 57.2 ± 10.9 mmol/mol [7.4 ± 1.0%]). Incidence by TBR70 was 12.1% for ≤1%, 10.2% for 1.1-3.9%, 10.6% for 4-6%, and 14.6% for >6%. Only those with TBR70 >6% and IAH had a significantly higher SHE risk (OR 3.32 [95% CI 1.40, 7.82]) compared with TBR70 ≤1% and no IAH. For TBR54, SHE incidence was 11.0% and 13.3% for categories <1% and ≥1%, respectively. Similarly, only individuals with TBR54≥1% and IAH had increased SHE risk (OR 2.99 [95% CI 1.46, 5.92]). Spline analysis showed low, stable SHE risk across TBR70 values in participants without IAH, with a non-linear pattern only in those with IAH.
Conclusions/interpretation: TBR alone is not discriminative for high-risk SHE but combining TBR with hypoglycaemia awareness status identifies those at the highest risk for both TBR70 and TBR54.
Trial registration: ClinicalTrials.gov NCT04657783.
Keywords: Continuous glucose monitoring; Impaired awareness of hypoglycaemia; Severe hypoglycaemia; Time below range; Type 1 diabetes.
© 2025. The Author(s).