Main Screen

The main screen has effectively 6 regions, some provide information and some give access to other menus.

  • Top left – Time, battery, sensor expire time
  • Top right – Settings menu
  • Centre left – Check glucose
  • Centre right – Review history
  • Bottom left – Alarms
  • Bottom right – Active insulin man

Settings Menu

The Settings menu is accessed through the “cog” icon on the top right of the main screen.

The reader has a clock and it stores the glucose readings with the time that the reading was taken. Typically the reader clock loses a couple of minutes a week, and you can set the clock via the Settings menu, or better, set it to the computer time via the desktop app. The Settings menu also allows you to set the Target Range. This sets your preferred upper and lower glucose values which affects how data is displayed and analysed by the reader and the desktop app.

The Settings menu also allows you to change the sounds that the reader will issue: high or low volume; with or without vibration. The Sounds menu is a bit confusing. What you really want is an option to switch off all sounds, or have vibrate rather than sounds. Instead you can turn on/off touch sounds, turn on/off notification sounds, set a global high or low volume, and only enable vibrate on notifications.

The “notifications” are used to indicate that data has been downloaded to the reader (bleep BLEEP!) or that the most recent glucose is low or high (BLEEP! BLEEP! BLEEP!). Since Libre is iCGM these warnings only occur when you swipe, so they should be treated as requiring immediate intervention. The problem is that the reader uses the same warning notification (BLEEP! BLEEP! BLEEP!) to indicate that the sensor is close to expiring. This expiration warning is irritating: you get it once daily for the few days before the sensor expires, and then on the expiration day you get it once an hour. Since the expiration warning is the same as an out of range warning it means that when you swipe your first reaction is that your glucose needs adjusting. In addition, the expiration warning shows a dialog box on the screen which you have to dismiss before you can see the actual reading. While such a notification may be useful for a new user, to remind them to purchase another sensor, they soon get irritating and so it would be much better if there was an option to disable it.

The Professional Options menu needs a password which is the same as other Abbott products and easily discovered through an internet search. This menu enables the insulin calculator, but the user glucose value this uses is from blood sticks and not from the Libre sensor. In effect, Abbott have simply used the software from one of their capillary blood testing meters. When you enable the insulin calculator, and regardless of whether you use it, the “active insulin man” will be visible in the bottom left hand corner of the main screen. This is a very rough indication of how much insulin will be active in your body based on the rapid insulin values you have entered and assuming that active insulin is roughly linear from the time it was injected until the duration of the insulin. The “active insulin man” has six levels giving a visual idea of how much insulin is active.

Finally, on the Settings menu there is a System Status menu item and of the three items the most useful one is the first, System Info. This lists the serial numbers of the reader and the three most recently used sensors, and when the current sensor will expire. If you need to have a sensor replaced under warranty then Abbott customer service will ask you for information on this screen.

History

The Review History on the main screen gives access to a menu with seven items:

  • Logbook
  • Daily Graph
  • Average Glucose
  • Daily Patterns
  • Time in Target
  • Low Glucose Events
  • Sensor Usage

These give you access to the three months of data stored on the reader and present them in various ways. The Logbook will have the scan data, that is, when you swipe and get the current reading from the sensor, the last sensor value and the associated arrow will be put in the Logbook. If you added notes to a value then you can view these by touching the item in the Logbook. If you view the Logbook within fifteen minutes of swiping then you can also add or edit notes on the last item (but only the last item) in the Logbook.

The Daily Graph shows 24 hours of the fifteen minute averaged data. The graph will shade in the area of the graph that represents the target range and your quest, of course, is to keep the data line within the shaded area. In addition, and within the limits of the small screen, there will be icons showing when you eat carbs and injected insulin. You can also use scroll keys to look at other days stored in the reader.

The small screen size is clearly a limitation. Worse, each graph is shown with a y axis that is 3 to 21 mmol/l, so if you are relatively well controlled most of the data will be in a small section of the screen. It would be nice to be able to tell the reader to scale the graph to the data, or to a range you specify.

The rest of the data screens show data averaged over 7 days, 14 days, 30 days or 90 days. The Average Glucose screen shows the total average over the selected time period as well as averages for the time period for the four quarters of the day shown as four bars : midnight to 6am, 6am to midday, midday to 6pm, and 6pm to midnight.

If you are interested in averages at particular times of the day a better graph is shown as the Daily Patterns. This gives an “average day” where each time shows a value averaged over the specified period for that particular time of the day. The graph indicates your targets with horizontal lines (no shading) so you can compare the average value with your target. The median (most frequent value) is shown as a black line and there is a shaded area where the edges of this are the 10th percentile and 90th percentile. That is, 90% of values are below the upper edge of the shaded area and 90% of values are above the lower edge (or conversely, 80% of data will be in the shaded area).

Perhaps the best measure of your control will be shown on the the Time in Target screen. This will show three bars (and figures) for the percentage of time you are in your specified target, and the percentage above and below target. Related to this is the Low Glucose Events screen, which shows the total number of “low glucose events” and how many of these are in the four quarters of the day. A “low glucose event” is defined as a glucose reading continuously lower than 3.9mmol/l for 15 minutes or more.

Finally, the Sensor Usage screen will show you the average number of times you scan every day and the proportion of the potential data that can be downloaded that you have obtained by scanning.

Alarms

The reader enables you to set twelve alarms (four pages of three alarms). To see the alarms touch on the alarm symbol in the bottom left corner of the main screen. If you have an alarm set then this symbol will also show the time that the next alarm will occur. This will show the Reminders screen that lists a maximum of three alarms. At the bottom there will be two buttons, the right one will always be [done] to go back to the main screen. The left button will be [more] if the screen is full (and you have set more than three alarms) and touching this button will display the next screen. If there are fewer than three alarms displayed then the left button will say [add new].

You can edit an existing alarm by touching the alarm on the screen, or you can create a new alarm by touching the [add new] button. In both cases the same screen will be shown and the only differences are the title: Edit Reminder or Set Reminder; and the buttons. This screen gives three values: the type (Check Glucose, Take Insulin, or simply, Alarm), the repeat option (Daily, Once and Timer) and the time. Strictly, Timer is not really a repeat option because this option will count down a specified number of hours and minutes rather that sound the alarm at a specified time. The Set Reminder screen will have a [cancel] and [save] button and the Edit Reminder screen will have a [delete] and [save] button. If you want to delete an alarm you should touch the item in the Reminders screen and then touch the the [delete] button. In addition, you can suspend an alarm through the Reminders menu.: next to each item in this menu is a slide button and when you touch this it will toggle between On and Off.

When an alarm sounds you will hear the notification sound and the screen will show a message related to the alarm type and it will have two buttons [snooze 15 mins] to increase the alarm time by fifteen minutes and [OK] to dismiss the alarm.

It is useful to set alarms to remind you to take insulin or eat carbs, but more useful is to set a reminder to check your glucose. If you get a reading of 7.5 with a diagonal up arrow and your upper target is 8, does this mean that your glucose will be heading to the teens, or is it about to peak? The diagonal arrow means that the glucose is increasing at less than 0.1 mmol/l per minute. In this case it may be a good idea to set a 15 minute alarm to check again, if the diagonal up arrow trend continues then in 15 minutes the glucose would be around 1.5 mmol/l higher (say, 9) and you may choose to have a small insulin correction to bring your glucose back in target. Similarly if you swipe and get a value of 5.0↓ then it may mean that in less than 10 minutes your glucose will be less than 4, so it may be a good idea to set an alarm to go off in less than 10 minutes and if the trend continues, correct with glucose.

It can get rather irritating to click the up and down arrows lots of times to set alarms. There are a few tricks that you can use to minimise the number of key presses. For example, say you want to set an alarm for one hour. If you do this with the Timer alarm you find that you will automatically get a 15 minutes set and you will have to remove this and set the alarm to one hour. The process is quite simple.

To set an alarm for one hour:

  1. Touch the alarm symbol in the bottom left of the Main Screen
  2. This will show the Reminders screen, touch the [add new] button
  3. The Repeat type will be set to Daily, so touch the [Daily] button to get the Reminder Schedule screen
  4. Touch the [Timer] button, this gives the Timer Duration screen
  5. The minutes setting will be automatically set to 15 minutes, if this is what you want you can simply touch the OK in the top right-hand corner. If you want more or less than this then you can touch the associated [up] and [down] buttons accordingly. If you want one hour touch the [down] button for the hour setting.
  6. You will find that the hour setting is set to 12 and the minutes setting will be reset to zero, the reason is that the maximum timer setting is twelve hours. Now touch the [up] button for the hour setting and you’ll find that it will change to 1. You now have the timer set to one hour, so you can touch the OK button in the upper right corner to set the alarm.
  7. On the Set Reminder screen touch the [save] button
  8. You’ll see that a new timer will be created and that it will already be counting down, click [done] to return to the main screen.

If you want to set an alarm for 30 minutes then you’ll have to start with a 15 minute timer and touch the [up] button multiple times until you get to 30. If you want a 55 minute timer then you can set a 1 hour timer as mentioned above and then reduce the minute value using the minute [down] button until you get 55, but this will give you a 1:55 timer, so you you now need to use the hour [down] button to reduce the hour setting to zero.

Using the Desktop Application