Time Below Range and Its Influence on Hypoglycemia Awareness and Severe Hypoglycemia: Insights From the Association of British Clinical Diabetologists Study

OBJECTIVE This study aimed to explore the relationship between time below range (TBR), impaired awareness of hypoglycemia (IAH), and severe hypoglycemia (SH). RESEARCH DESIGN AND METHODS This cross-sectional study analyzed data from individuals with diabetes using continuous glucose monitors (CGMs) in the Association of British Clinical Diabetologists audit. Hypoglycemia awareness was assessed via the Gold score (≥4 denoting IAH), and SH was defined as hypoglycemia requiring third-party assistance. Logistic regression was used to determine the association between TBR percentage (<70 mg/dL; 3.9 mmol/L) at first follow-up and follow-up Gold score and SH incidence. The Youden J index identified optimal TBR percentage cutoffs for detecting IAH and SH. RESULTS The study included 15,777 participants, with follow-up TBR and SH data available for 5,029. The median TBR percentage was 4% (interquartile range 2–6.6%), with 42% meeting the recommended TBR of ≤4%. Adjusted for age, sex, and BMI, TBR was significantly associated with SH (P < 0.001) and IAH (P = 0.005). Optimal TBR cutoffs for identifying IAH and SH were 3.35% and 3.95%, yielding negative predictive value (NPV) values of 85% and 97%, respectively. CONCLUSIONS Our findings support the international consensus recommending a TBR of <4% in type 1 diabetes, with high NPV values suggesting the utility of TBR in screening for SH.