No Result: A Surprising Adverse Event for Continuous Glucose Monitors

Recently, an article described no result as the most frequent adverse event for blood glucose meters. ¹ The leading cause was failure to power on the glucose meter. Since there is nothing to power on for continuous glucose monitors (CGMs) it was a surprise to learn that the most frequent adverse event was again, no result.

The same procedure to analyze data was used as previously described, ¹ which involved queries to a SQL Server database created from available FDA files ² and visual basic for application programs on the extracted data in Excel. There were 711,114 CGM adverse event records with 356,249 distinct CGM events. The higher number of records include manufacturer responses to each event. Table 1 shows the causes for no result. Inaccuracy and other causes accounted for the rest the 356,249 events that were examined.

Table 1.

Leading Causes for Continuous Glucose Monitor No Event.

Cause	N	Percent
transmitter problem	213,589	60.0%
early sensor expiration	15,402	4.3%
missing or detached sensor	4,594	1.3%
app crash	3,246	0.9%
error code	1,789	0.5%
Total (no result)	238,620	67.0%

Every week, a CGM produces 2,016 glucose results. There was not enough information to know when the no result event occurred and it is possible in some cases, that the no result event occurred when a sensor was being changed. Also, for 9,551 events (2.7%), the manufacturer commented that there was off-label use as the patient either used an unsupported app or an unsupported sensor location. Future evaluations should document the frequency when the CGM fails to provide a result.