Real-World Patterns of Daytime and Nocturnal Hypoglycemia during Flash Continuous Glucose Monitoring

This study evaluated patterns of daytime and nocturnal hypoglycemia during flash continuous glucose monitoring using the FreeStyle Libre^TM system. Users scan the sensor to collect the current glucose, trend, and up to 8 hours of glucose readings which are automatically stored every 15 minutes. The internet-connected PC-based software uploads the de-identified 90-day reader data to a database. De-identified data from September 2014 to September 2017 of all sensors with at least 120 hours of operation were analyzed from 237,747 readers and 1,569,588 sensors worldwide (88% from Europe). Readers were ranked by scan frequency and allocated to 20 equally sized groups. The association of significant hypoglycemia (≤54 mg/dL) and scan rate were analyzed. Users performed a mean (SD) of 13.2 (9.0) glucose scans per 24 hours, with 11.5 (8.1) during the day (06:00-23:00) and 1.7 (1.5) during the night (23:00-06:00). Time in significant hypoglycemia (≤54 mg/dL) decreased from 24.2 to 15.2 minutes/day comparing low with high frequency scanners during the 17-hour day period (p<0.001), with a similar pattern overnight (19.0 and 12.7 minutes/night, p<0.001). When expressed as a proportion of time, hypoglycemia accounted for 2.4 to 1.5% of daytime glucose (for low to high frequency scanners), prevalence of night time hypoglycemia was 4.5 to 3.0%. The benefits of scanning frequently during the day are evident at night time.