User guide

Sometimes the Guardian RT will alert when the blood glucose levels are not high. When the Guardian RT
High Alert was set at 250 mg/dL (13.8 mmol/L) in this study, 13.1% of the results were considered false
alerts (actual blood glucose values are less than 225 mg/dL (12.5 mmol/L)). This percentage may be
exaggerated because blood glucose may be rising when the Guardian RT alerts. The following table shows
the percent of High Glucose readings correctly identified by the Guardian RT for specific settings.
Guardian RT High Alert
Setting (mg/dL)
Guardian RT High Alert
Setting (mmol/L)
True Alert Rate* False Alert Rate**
190 10.6 94% 40%
200 11.1 91% 36%
225 12.5 81% 21%
250 13.8 64% 13%
* True Alert Rates are the % of times when the glucose level was at or above the alert setting and the alert
sounded.
** False Alerts Rates are the % of times when the Guardian RT Sensor alarmed but the blood glucose level
was lower than the alert setting.
Decreasing the High Alert settings will improve the ability to detect high blood glucose events, but it will
also increase the frequency of Guardian RT false alerts for blood glucose levels not above the target value.
You should consider this trade-off between the improved ability to detect true high blood glucose versus
the increased number of false alerts when setting the high alert threshold.
Sensor accuracy 153
Appendix A