Time below range alone is insufficient to identify severe hypoglycaemia risk in type 1 diabetes—the critical role of hypoglycaemia awareness: results from the SFDT1 study

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<p></p>