User Manual

Performance Characteristics 91
The High Glucose Alert
The High Glucose Alert was evaluated for its ability to detect glucose levels at 250 mg/dl (13.8 mmol/l), or
above, using the YSI analyzer. As a reference, with the High Glucose Alert set at 250 mg/dl 13.8 mmol/l),
53% (195/365) of high glucose events were detected by the Guardian RT. Better detection of high blood
glucose can be obtained by setting the High Glucose Alert level lower. For example, setting the High
Glucose Alert at 190 mg/dl (10.6 mmol/l), instead of 250 mg/dl (13.8 mmol/l), increases the ability to
detect high blood glucose levels from 53% to 85% (see Table 5.6).
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, 7.2% 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. Table 5.6 shows the percent of High
Glucose readings correctly identified by the Guardian RT for specific settings.
Table 5.6
* 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.
Guardian RT High
Alert Setting
(mg/dl)
Guardian RT High
Alert Setting
(mmol/l)
True Alert Rate* False Alert
Rate**
190 10.6 85% 64%
200 11.1 81% 58%
225 12.5 67% 40%
250 13.8 53% 25%