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Percent Time Below Range Is Strongly Associated with Clinically Important Level 2 Hypoglycemia Events in Individuals
Peter Calhoun1, Richard T Liggins2, Zoey Li1
1JAEB Center for Health Research, Tampa, Florida, USA.
Diabetes Technology & Therapeutics
|June 23, 2026
Summary
Continuous glucose monitoring (% time <54 mg/dL) strongly correlates with Level 2 hypoglycemic events in type 1 diabetes. However, event duration impacts the relationship, suggesting both factors are crucial for assessing hypoglycemia risk.
Area of Science:
- Endocrinology
- Diabetes Technology
- Metabolic Research
Background:
- Hypoglycemia is a significant concern for individuals with type 1 diabetes (T1D).
- Continuous glucose monitoring (CGM) provides detailed insights into glucose fluctuations.
- Level 2 hypoglycemic events (L2 events) are defined as glucose levels <54 mg/dL for at least 15 minutes.
Purpose of the Study:
- To evaluate the relationship between CGM-measured % time <54 mg/dL (%T < 54) and the occurrence of L2 events in T1D.
- To determine if L2 event duration modifies the association between %T < 54 and L2 event frequency.
Main Methods:
- Analysis of data from 1532 participants with T1D across eight clinical trials (3-6 months duration).
- Inclusion of participants using automated insulin delivery (AID), CGM without AID, and self-monitoring blood glucose (SMBG) without CGM.
- Statistical examination of correlations between %T < 54 and L2 event rates, considering L2 event duration.
Main Results:
- A strong correlation (r = 0.97) was observed between %T < 54 and L2 event rate.
- The predicted weekly L2 event rate varied based on L2 event duration: 2.4 events (short, <30 min), 1.9 events (medium, 30-60 min), and 1.2 events (long, >60 min) per 1% T < 54.
- Participants meeting targets (<1% T < 54) averaged 0.6 L2 events/week, while those not meeting targets (≥1% T < 54) averaged 2.9 L2 events/week.
Conclusions:
- CGM-measured %T < 54 and L2 event frequency are strongly correlated in T1D.
- L2 event duration significantly influences this relationship, highlighting the importance of reporting both frequency and duration.
- Time-below-range metrics effectively summarize hypoglycemia exposure by incorporating both frequency and duration.
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