Some points to consider in the daily management of diabetes using the Medtronic 722 Paradigm Real Time Systems

The Paradigm 772 Real Time System can be a very effective management tool but for a first time user, there a few features that may be frustrating. This is particularly true if you have a “set it and forget it” mindset. But fortunately this excellent management tool just takes a little understanding and a bit of effort (not much) to get the most out of it. Don’t forget that you don’t have to turn every feature “on” at the first instant. Work into it gradually. The following points are based on my own experience and from what I have gleaned from other users.

1. Alarm Management


Many users express concern at the amount of time it takes to manage the number of alarms that are activated. It appears that the alarm system is very comprehensive and very flexible. Users are gradually changing from a position of, “Turn them all on and narrow the limits and ranges” to one of “What is important to me”. The other approach is for the limits to be widened where there is less immediate impact resulting from an excursion out side a limit. It’s funny how all the alarms seem to go off in the middle of the night. So review your alarm management with your CDE and it is most likely that significant improvements can be made.


The WEAK SIGNAL often goes off at night when you are sleeping. Often the pump only receives the signals on a weakened or intermittent basis from the transmitter due to location of the two units. If you have the transmitter on one side of your body and the pump on the other side, sometimes the signals just do not get through. So “rig-a-system” that keeps them in close proximity and you will avoid a lot of these alarms.

Managing the “METER BG NOW” Alarm

Nothing is more annoying than being awakened at night to the Sensor demanding a BG reading NOW. The solution is managing this requirement more effectively. Make sure that the 12 hour requirement is started before 9 AM. If you start it at say 8 AM, the next required reading will come at 8 PM.

By the way have you ever been in a position where the Sensor is asking for a new BG reading and you haven’t got your meter with you or are not in a position to do an immediate BG reading, put in the reading displayed when it asked for a new one. Make sure you do a BG ASAP and input it to the Sensor. This is not a good practice but may get you out of a jam.

2. Restarting a Sensor after an “SENSOR END” message.

The Sensor has a life of 72 hrs. or 3 days (Sensor Features User Guide, p. 36). At the end of 72 hours, a SENSOR END message will appear and the Sensor will stop working and a new Sensor should be inserted. There is no doubt that this is the preferred method and every effort must be made to adhere to this time frame.

However, all users will eventually run across a situation where they don’t have immediate access to a new Sensor or want to extend the life of a current Sensor. In this case, the existing Sensor will likely be able to be restarted. Simply do a Sensor >Sensor Start > New Sensor from the Main Menu and follow the screen instructions. They will also call for a calibration BG after two hours; however, this time will likely be much shorter (in the order of 10 or 15 minutes), presumably because the Sensor is already in a stable state). This procedure may get a user out of a bind. Make sure that the Sensor site is checked frequently for infection. Many users report that they can use the Sensor for 8 or 9 days.

3. When Do I Have to Change a Sensor?

The most frequent sign of a Sensor failing is a continued WEAK SIGNAL alarm. If you take all the necessary actions regarding this alarm and it keeps on occurring, it is likely to be followed by a LOST SENSOR alarm from which you can’t recover. You can attempt to use the FIND LOST SENSOR function but if the Sensor life is truly over, this will not work. Once you have used the Sensor for awhile you will get to know about how long they last and can plan accordingly. There are other conditions that require changing a Sensor, but these appear to be reasonably few and far between.

The situation that is a bit frustrating is when you insert a new Sensor and you get a “gusher”. If the bleeding is severe, then you don’t have much choice except to remove the Sensor, discard it, move to another site and insert another new Sensor.

4. Understanding the Data Provided by the Sensor

It is very important to understand the data that is being provided by the Continuous Glucose Sensor. It may not be exactly as you believe and there are three points that should be fully understood to use the data to its fullest in daily management practices.

Accuracy: The accuracy of the Sensor is described very well in the Sensor Features User Guide, however it is quite complex and would be much more useful if simplified. Don’t forget that 20% of a Sensor BG value of 10.0 mmol/L is 2.0 mmol/L. Keep this in mind when comparing the Sensor BG with a Meter BG. Also keep in mind the accuracy of the Meter which may be in the 7% to 10% range. The readings from the Sensor and the Meter are seldom absolute and the two values seldom agree unless the BG levels are constant over a significant period of time. Not only are differences between CCGM and capillary BG due to system errors but these differences can be exacerbated by the rate that the BG is increasing or decreasing and the ensuing delay.

Delay: The other thing to keep in mind is the delay in the Sensor readings. The delays are caused by the slower absorption of glucose into the interstitial fluid (Sensor) than into the whole blood.(Meter) Users are reporting that the Sensor BG is 20 to 30 minutes behind the actual reading. Since this delay is user specific, it is important that you try to get a handle on this. This delay may be difficult to separate from the onset time of the insulin so don’t try to establish the Delay Time just after taking a large bolus. Work with your CDE on this aspect

Trends: The good news of all this is the slope of the BG changes is very consistent with those taken by other means. If users can count on the trends being accurate then it is the trends that users should focus on in their daily management schemes. After all, much of what daily diabetes management is all about is predicting the short term future. As one user put it “Now we don’t have to react to something in the past, we can look ahead and do a bit of planning” or as my Diabetes Specialist put it, “It’s all about TRENDS”. Discuss all this with your Doctor or CDE

Ross Douglas
A 722 RT System User
May 26, 2006